ISSN 1453 – 7303 “HIDRAULICA” (No. 2/2013) Magazine of Hydraulics, Pneumatics, Tribology, Ecology, Sensorics, Mechatronics

CONTENTS

• WHAT TO DO WITH A HYBRID DRIVE SYSTEM? Krzysztof Kędzia

7 – 15

• ADAPTIVE ROBUST CONTROL APPLICABLE ON VARIABLE PUMPS Daniel Vasile BANYAI, Ioan-Lucian MARCU

16 – 24

• ASSISTED OPTIMIZATION OF THE HYDRAULIC CYLINDER BY USING THE ROOTS LOCUS CHARACTERISTICS AND LABVIEW INSTRUMENTATION

Adrian Olaru, Serban Olaru

25 – 38

• DIVISIONS OR SUMMATIVE HYDRAULIC FLOWS STANDARD

Victor BALASOIU, Ilarie BORDEASU

39 – 43

• THE INCREASING OF THE TRIBOLOGICAL PERFORMANCES OF THE FLUID POWER EQUIPMENTS

Ph. D. Eng. Corneliu CRISTESCU, Prof. Ph.D.Eng. Iile FILIP Assoc. Prof. Ph.D.Eng. Alexandru RADULESCU, Assoc. Prof. Ph.D.Eng. Sorin CANANAU

44 – 53

• STAINLESS STEEL COLD-WORK HARDENING THROUGH CAVITATION Ilare BORDEAȘU, Ion MITELEA, Mircea Octavian POPOVICIU, Marcela SAVA

54 – 59

• SIZING SOLAR CIRCUIT CORRESPONDING TO A SOLAR INSTALLATIONS FOR PREPARATION HOT WATER SYSTEMS Adriana Gruia

60 – 64

• THE 3D BLADE SURFACE GENERATION FOR KAPLAN TURBINES USING ANALYTICAL METHODS AND CAD TECHNIQUES Teodor MILOS, Mircea Octavian POPOVICIU, Ilare BORDEASU, Rodica BADARAU, Adrian BEJ, Dorin BORDEASU

65 – 74

• COMPUTATION OF THE COMPLIANCE MATRIX FOR ROTARY LIP SEAL Elgadari M, Fatu A, Hajjam M, Belhaq M

75 – 83

• MONITORING OF PHYSICAL INDICATORS IN WATER SAMPLES Rusănescu Carmen Otilia, Rusănescu Marin, Stoica Dorel

84 - 89

• APPLICATIONS OF PROPORTIONAL PNEUMATIC EQUIPMENT IN INDUSTRY Sava ANGHEL, Gabriela MATACHE, Ana–Maria POPESCU, Iulian-Cezar GIRLEANU

90 - 95

• AMPLITUDES INFLUENCE ON THE PROCESS OF SEPARATION A GRAIN SELECTOR

Stoica DOREL

96 - 102

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ISSN 1453 – 7303 “HIDRAULICA” (No. 2/2013) Magazine of Hydraulics, Pneumatics, Tribology, Ecology, Sensorics, Mechatronics

MANAGER OF PUBLICATION

- PhD. Eng.Petrin DRUMEA - Manager - Hydraulics and Pneumatics Research Institute in Bucharest,

Romania

CHIEF EDITOR - PhD.Eng. Gabriela MATACHE - Hydraulics and Pneumatics Research Institute in Bucharest, Romania

EXECUTIVE EDITORS

- Ana-Maria POPESCU - Hydraulics and Pneumatics Research Institute in Bucharest, Romania

- Valentin MIROIU - Hydraulics and Pneumatics Research Institute in Bucharest, Romania

SPECIALIZED REVIEWERS - PhD. Eng. Heinrich THEISSEN – Scientific Director of Institute for Fluid Power Drives and Controls IFAS,

Aachen - Germany

- Prof. PhD. Eng. Henryk CHROSTOWSKI – Wroclaw University of Technology, Poland

- Prof. PhD. Eng. Pavel MACH – Czech Technical University in Prague, Czech Republic

- Prof. PhD. Eng.Alexandru MARIN – POLITEHNICA University of Bucharest, Romania

- Assoc.Prof. PhD. Eng. Constantin RANEA – POLITEHNICA University of Bucharest, Romania

- Lecturer PhD.Eng. Andrei DRUMEA – POLITEHNICA University of Bucharest, Romania

- PhD.Eng. Ion PIRNA - General Manager - National Institute Of Research - Development for Machines and

Installations Designed to Agriculture and Food Industry – INMA, Bucharest- Romania

- PhD.Eng. Gabriela MATACHE - Hydraulics & Pneumatics Research Institute in Bucharest, Romania

- Lecturer PhD.Eng. Lucian MARCU - Technical University of Cluj Napoca, ROMANIA

- PhD.Eng.Corneliu CRISTESCU - Hydraulics & Pneumatics Research Institute in Bucharest, Romania

- Prof.PhD.Eng. Dan OPRUTA - Technical University of Cluj Napoca, ROMANIA

Published by: Hydraulics & Pneumatics Research Institute, Bucharest-Romania Address: 14 Cuţitul de Argint, district 4, Bucharest, cod 040557, ROMANIA Phone: +40 21 336 39 90; +40 21 336 39 91 ; Fax:+40 21 337 30 40 ; E-mail: ihp@fluidas.ro Web: www.ihp.ro with support of: National Professional Association of Hydraulics and Pneumatics in Romania - FLUIDAS E-mail: fluidas@fluidas.ro Web: www.fluidas.ro HIDRAULICA Magazine is indexed in the international databases:

HIDRAULICA Magazine is indexed in the Romanian Editorial Platform:

ISSN 1453 – 7303; ISSN – L 1453 – 7303

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ISSN 1453 – 7303 “HIDRAULICA” (No. 2/2013) Magazine of Hydraulics, Pneumatics, Tribology, Ecology, Sensorics, Mechatronics

WHAT TO DO WITH A HYBRID DRIVE SYSTEM? Krzysztof Kędzia1

1Wrocław University of Technology, Institute of Machines Design and Operation

e-mail: krzysztof.kedzia@pwr.wroc.pl

Abstract: Do hybrid drive are the future? Limited resources of fossil fuels causing increasingly frequent questions about the future of propulsion systems. In this paper, on the basis of available information, was described the basic structure, types, and the potential benefits of multisources drive systems. The author's intention is to initiate a discussion which type of drive system: hydraulic, pneumatic, mechanical, electrical, is potentially the best solution to use in the future. Keywords: Hybrid drive system, ecology, energy, efficiency.

1. Introduction.

Drive systems of machines and vehicles with an accumulation of energy is one of the elements of environmental technology. In a fast-changing cyclically repeated external loads of working machines and vehicles drive systems provide a reduction of primary energy consumption, and therefore exhaust gases emissions. They also allow to recuperate a kinetic or potential energy. Generally, lower energy consumption of drive systems of machines and vehicles, can be obtain by [4]:

- increasing an efficiency of drive system components, - appropriate matching of high-efficient zones of components of powertrain, - use of multi-source (hybrid) drive system, allowing to recuperate a kinetic or potential energy.

To design rational drive systems there should be used above listed postulates. It requires knowledge from transformation, transmission, distribution and energy recuperation field and meet several additional requirements. This applies in particular:

- Knowledge of the characteristics of the load (energetic characteristic), including flow variables (linear and angular velocity, flow rate) and effort variables (power, torque, pressure). It could be represented as: operating point, load curves, area of work or cycle work, or in the spectrum of loads.

- Knowledge of an energy characteristics (energy efficiency or losses). - Evaluation of an energy efficiency of alternative solutions of the drive system for the same load

conditions. - Problems solving connected with structures and components selection for the drive system. - Problems solving connected with controls issues, in particular the synthesis of control systems.

In the literature, the concept of multi-sources (or hybrid) drive systems, is known for several decades [1], [2], [3], [4]. Research and development on these issues, from economic and technological reasons, were periodic- sometimes very intensive, sometimes weak activity. They were closely related with the fuel crisis. Nowadays R&D activity in this area is more and more connected with an environmental aspects.

"Keeping up" of energy source for variable load is characteristic for classic drive systems. It is directly connected with the energy efficiency of the system, which often reaches values even below 10%. It has a significant impact on the operating costs such as: fuel and lubricants consumption, or durability of the drive system. This applies in particular to internal combustion engines.

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One of the ways to solve this problem is multisources (hybrid) drive systems, characterized by the cooperation of at least two energy sources, wherein at least one of them must be the secondary source of energy.

The concept of "primary source of energy" should be understood as a source of energy with constant parameters, providing energy to the system regardless of the changes taking place in the load. This may be for example a heat engine. The "primary source of energy" is characterized by irreversible energy flow- only from source to the system.

The term "secondary source of energy" (an accumulator) means a device for accumulating potential or kinetic energy. The battery stores the surplus and / or recoverable energy. The accumulation can be realized by electrochemical, hydraulic or mechanical batteries. Secondary source of energy is characterized by reversible work.

Due to the direction of energy flow and location of the sources, there are two types of structures of hybrid systems:

- series (fig.1), - parallel (fig.2).

Fig. 1. Schema of series hybrid drive system.

Fig. 2. Schema of parallel hybrid drive system [4].

There are many solutions of secondary sources of energy. The most widespread and historically oldest, is undoubtedly a mechanical press (serial system), in which the electric motor operates with power equal to the average power in the cycle. Increased energy demand is met from secondary sources of energy- in this case flywheel. When the press is in idling mode, flywheel gathers an energy supplied to the system by an electric motor. Other examples could be: the steam engine, compressor or IC engine, where the flywheel is used to stabilization of angular velocity [5].

CONTROL SYSTEM

PRIMARY SOURCE OF ENERGY

SECONDARY SOURCE OF ENERGY

LOAD

PRIMARY SOURCE OF ENERGY

SECONDARY SOURCE OF

LOAD

CONTROL SYSTEM

Emech Emech

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Nowadays more and more companies propose a hybrid machinery and equipment of propulsion systems. Information on the details of construction and principles of their controls, is limited to the manual, because of trade secret or competition between companies. In some cases, the construction of hybrid machines is a result of experimental tests and an engineers intuition and their experience

2. Energy sources for hybrid vehicles

There are a few power sources for hybrid vehicles [5]:

2.1. On-board or out-board rechargeable energy storage system (RESS).

A rechargeable energy storage system or RESS is a system that stores energy for delivery of power and which is rechargeable. Production storage systems use electric rechargeable traction batteries, electric double-layer capacitors or flywheel energy storage [21].

2.2. Coal, wood or other solid combustibles.

Solid fuel refers to traditional types of combustible solid fuels like firewood and coal. While these fuel types are readily available (some of them actually grow on trees), not all of them are sustainable in the long term. Coal, for example, is a fossil fuel, and its use in the production of electricity is said to make it the largest contributor to the human-made increase in CO2 in the atmosphere. The use of coal in solid fuel heaters is, however, increasingly uncommon. Types of solid fuel:

- wood, - charcoal, - peat, - coal, - hexamine fuel tablets, - organic pellets.

2.3. Electricity, Electromagnetic fields, Radio waves.

Electricity is the set of physical phenomena associated with the presence and flow of electric charge. Electricity gives a wide variety of well-known effects, such as lightning, static electricity, electromagnetic induction and the flow of electrical current. In addition, electricity permits the creation and reception of electromagnetic radiation such as radio waves [5].

2.4. Compressed or liquefied natural gas.

Compressed natural gas (CNG) is a fossil fuel substitute for gasoline (petrol), Diesel fuel, or propane/LPG. Although its combustion does produce greenhouse gases, it is a more environmentally clean alternative to those fuels, and it is much safer than other fuels in the event of a spill (natural gas is lighter than air, and disperses quickly when released). CNG may also be mixed with biogas, produced from landfills or wastewater, which doesn't increase the concentration of carbon in the atmosphere [22].

CNG is made by compressing natural gas (which is mainly composed of methane [CH4]), to less than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 200–248 bar (2900–3600 psi), usually in cylindrical or spherical shapes.

2.5. Human powered e.g. pedalling or rowing.

Human powered transport includes walking, bicycles, velomobiles, row boats, and other environmentally friendly ways of getting around. In addition to the health benefits of the exercise provided, they are far more environmentally friendly than most other options. The only downside is the speed limitations, and how far one can travel before getting exhausted [5].

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2.6. Hydrogen.

A hydrogen vehicle is a vehicle that uses hydrogen as its onboard fuel for motive power. Hydrogen vehicles include hydrogen fueled space rockets, as well as automobiles and other transportation vehicles. The power plants of such vehicles convert the chemical energy of hydrogen to mechanical energy either by burning hydrogen in an internal combustion engine, or by reacting hydrogen with oxygen in a fuel cell to run electric motors. Widespread use of hydrogen for fueling transportation is a key element of a proposed hydrogen economy [11].

2.7. Petrol or Diesel fuel.

Petrol and diesel are petroleum-derived liquid mixtures used as fuels. Though both have similar base product but have different properties and usage.

Petrol is a petroleum-derived liquid mixture consisting mostly of aliphatic hydrocarbons and enhanced with aromatic hydrocarbons toluene, benzene or iso-octane to increase octane ratings, primarily used as fuel in internal combustion engines. Diesel is a specific fractional distillate of petroleum fuel oil or a washed form of vegetable oil that is used as fuel in a diesel engine invented by German engineer Rudolf Diesel [8].

2.8. Solar.

Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar energy technologies include solar heating, solar photovoltaics, solar thermal electricity and solar architecture, which can make considerable contributions to solving some of the most urgent problems the world now faces

The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 3,850,000 exajoules (EJ) per year.[6] In 2002, this was more energy in one hour than the world used in one year

2.9. Wind.

Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space. Winds are commonly classified by their spatial scale, their speed, the types of forces that cause them, the regions in which they occur, and their effect.

3. Engine type.

3.1. Hybrid electric-petroleum vehicles

When the term hybrid vehicle is used, it most often refers to a Hybrid electric vehicle. These encompass such vehicles as the Saturn Vue, Toyota Prius, Toyota Camry Hybrid, Ford Escape Hybrid, Toyota Highlander Hybrid, Honda Insight, Honda Civic Hybrid, Lexus RX 400h and 450h and others. A petroleum-electric hybrid most commonly uses internal combustion engines (generally gasoline or Diesel engines, powered by a variety of fuels) and electric batteries to power the vehicle. There are many types of petroleum-electric hybrid drivetrains, from Full hybrid to Mild hybrid, which offer varying advantages and disadvantages [5].

3.2. Continuously outboard recharged electric vehicle (COREV).

Given suitable infrastructure, permissions and vehicles, BEVs can be recharged while the user drives. The BEV establishes contact with an electrified rail, plate or overhead wires on the highway via an attached conducting wheel or other similar mechanism (see Conduit current collection). The BEV's batteries are recharged by this process on the highway and can then be used normally on

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other roads until the battery is discharged. Some of battery-electric locomotives used for maintenance trains on the London Underground are capable of this mode of operation. Power is picked up from the electtrified rails where possible, switching to battery power where the electricity supply is disconnected.

3.3. Hybrid fuel (dual mode).

In addition to vehicles that use two or more different devices for propulsion, some also consider vehicles that use distinct energy sources or input types ("fuels") using the same engine to be hybrids, although to avoid confusion with hybrids as described above and to use correctly the terms, these are perhaps more correctly described as dual mode vehicles [5]:

- Some electric trolleybuses can switch between an on board diesel engine and overhead electrical power depending on conditions (see dual mode bus). In principle, this could be combined with a battery subsystem to create a true plug-in hybrid trolleybus, although as of 2006[update], no such design seems to have been announced.

- Flexible-fuel vehicles can use a mixture of input fuels mixed in one tank — typically gasoline and ethanol, or methanol, or biobutanol.

- Bi-fuel vehicle:Liquified petroleum gas and natural gas are very different from petroleum or diesel and cannot be used in the same tanks, so it would be impossible to build an (LPG or NG) flexible fuel system. Instead vehicles are built with two, parallel, fuel systems feeding one engine. While the duplicated tanks cost space in some applications, the increased range and flexibility where (LPG or NG) infrastructure is incomplete may be a significant incentive to purchase.

- Some vehicles have been modified to use another fuel source if it is available, such as cars modified to run on autogas (LPG) and diesels modified to run on waste vegetable oil that has not been processed into biodiesel.

- Power-assist mechanisms for bicycles and other human-powered vehicles are also included (see Motorized bicycle).

3.4 Fluid power hybrid.

Hydraulic and pneumatic hybrid vehicles use an engine to charge a pressure accumulator to drive the wheels via hydraulic or pneumatic (i.e. compressed air) drive units. In most cases the engine is detached from the drivetrain merely only to change the energy accumulator. The transmission is seamless.

3.5 Elctric-human power hybrid vehicle.

Another form of hybrid vehicle are human power-electric vehicles. These include such vehicles as the Sinclair C5, Twike, electric bicycles, and electric skateboards [5].

4. Environmental issues.

4.1. Fuel consumption and emissions reductions.

Start/Stop: In the NEDC (New European driving cycle) a fuel consumption reduction of 5-8 percent can be achieved with engine stop at vehicle standstill (fig. 3) [23].

Optimised operation: Engine operation with low engine load can be substituted by electric driving. Further, the combination of combustion engine and electric machine offers the possibility to shift the engine load point

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Brake energy recovery: Recovery of the brake energy results in a fuel consumption reduction of 3-10 percent in the NEDC, depending on the layout of the hybrid powertrain, the maximum power of the electric machine and the efficiencies of the powertrain components

Fig.3 . Fuel consumption benefit of hybrid vehicles [23].

Figure 4 shows the simulated fuel consumption values for a conventional vehicle, the parallel hybrid and the parallel hybrid with fuel cell range extender.

Fig. 4. Simulated fuel consumption values for a conventional vehicle, the parallel hybrid and the parallel hybrid with fuel cell range extender [23].

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Hybridisation offers a big potential to reduce the fuel consumption especially in the ECE (urban part of the NEDC cycle) as all hybrid features – start/stop, electric driving and energy recovery – can be fully used.

4.2. Hybrid vehicle emissions.

Hybrid vehicle emissions today are getting close to or even lower than the recommended level set by the EPA (Environmental Protection Agency). The recommended levels they suggest for a typical passenger vehicle should be equated to 5.5 metric tons of carbon dioxide. The three most popular hybrid vehicles, Honda Civic, Honda Insight and Toyota Prius, set the standards even higher by producing 4.1, 3.5, and 3.5 tons showing a major improvement in carbon dioxide emissions. Hybrid vehicles can reduce air emissions of smog-forming pollutants by up to 90% and cut carbon dioxide emissions in half.

4.3. Environmental impact of hybrid car battery.

Fig. 5. Comparison of energy densities of rechargeable batteries [18].

Though hybrid cars consume less gas than conventional cars, there is still an issue regarding the environmental damage of the hybrid car battery. Today most hybrid car batteries are one of two types: 1) nickel metal hydride, or 2) lithium ion; both are regarded as more environmentally friendly than lead-based batteries which constitute the bulk of petro car starter batteries today. There are many types of batteries (fig. 5). Some are far more toxic than others. Lithium ion is the least toxic of the three mentioned above.[19]

The toxicity levels and environmental impact of nickel metal hydride batteries the type currently used in hybrids are much lower than batteries like lead acid or nickel cadmium. However, nickel-based batteries are known carcinogens, and have been shown to cause a variety of teratogenic effects.[20]

The Lithium-ion battery has attracted attention due to its potential for use in hybrid electric vehicles. Hitachi is a leader in its development. In addition to its smaller size and lighter weight, lithium-ion batteries deliver performance that helps to protect the environment with features such as improved charge efficiency without memory effect. The lithium-ion batteries are appealing because they have

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the highest energy density of any rechargeable batteries and can produce a voltage more than three times that of nickel–metal hydride battery cell while simultaneously storing large quantities of electricity as well. The batteries also produce higher output (boosting vehicle power), higher efficiency (avoiding wasteful use of electricity), and provides excellent durability, compared with the life of the battery being roughly equivalent to the life of the vehicle. Additionally, use of lithium-ion batteries reduces the overall weight of the vehicle and also achieves improved fuel economy of 30% better than petro-powered vehicles with a consequent reduction in CO2 emissions helping to prevent global warming [19].

4.4. Raw materials increasing costs.

Fig. 6. Abundance of elements in the Earth crust per million of Si atoms [11], [12].

There is an impending increase in the costs of many rare materials (fig.6) used in the manufacture of hybrid cars [15]. For example, the rare earth element dysprosium is required to fabricate many of the advanced electric motors and battery systems in hybrid propulsion systems [15], [16]. Neodymium is another rare earth metal which is a crucial ingredient in high-strength magnets that are found in permanent magnet electric motors[13].

Nearly all the rare earth elements in the world come from China [14], and many analysts believe that an overall increase in Chinese electronics manufacturing will consume this entire supply by 2012 [15]. In addition, export quotas on Chinese rare earth elements have resulted in an unknown amount of supply [11],[14].

A few non-Chinese sources such as the advanced Hoidas Lake project in northern Canada as well as Mount Weld in Australia are currently under development; however, the barriers to entry are high [17] and require years to go online.

5. Conclusions.

So what we have to do? We have to planing future without oil.

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With the price of crude hovering above $140 a barrel there is significant pressure to reduce and manage our energy consumption. Goldman Sachs has predicted that we will soon hit $200 per barrel [24].

Politicians and commentators are quick to offer solutions or attribute blame. However many of them deny the fact that in the not too distant future, supply will not be able to keep up with demand. Drilling cannot fix this and speculators are not to blame. Speculators are simply reading the markets. Making pariahs out of speculators is yet another way to avoid the reality of the energy problems we face. And drilling for oil in Alaska or off America's shores will further degrade the environment and do nothing to reduce the price of oil [24].

Even the much maligned government of China has put energy efficiency on the top of their agenda. Within the realm of today's technology it is entirely possible to achieve a 10% reduction in energy consumption. Although inflation is a real problem, there are some upsides to increased oil prices. The high price of oil exerts pressure to reduce consumption and research alternatives [24].

Although oil is still part of the energy equation, in the future we will have a more diversified energy economy that is much less dependent on oil. If we are to be weaned off of oil we will need to focus on energy in a methodical way. From a policy point of view we need incentives and disincentives in support of efficiency and alternatives. We need national and global energy strategies [24].

REFERENCES

[1] A. Szumanowski, “Hybrid electric vehicle drive design“, Institute for Sustainable Technologies- NRI, ISBN 83-7204-456-2, Poland, 2006.

[2] J.R. Cristobal Mateo, "Multi-Criteria Analysis in the Renewable Energy Industry", Springer- Verlang London Limited, 2012.

[3] C. Cristescu, "Recuperarea energiei cinetice la franarea autovehiculelor", Editura AGIR, 2008. [4] K. Kędzia, "Metoda optymalizacji energetycznej i ekologicznej hydrostatycznego wieloźródłowego układu

napędowego", Monography, Wrocław University of Technology, 2004. [5] http://en.wikipedia.org/wiki/Greenhouse_gases. [6] http://www.thegreenmarketoracle.com/2011/12/ev-sales-predictions-in-us.html. [7] http://en.wikipedia.org/wiki/Green_vehicle#National_and_international_promotion. [8] http://www.epa.gov/oms/technology/research/how-it-works.htm. [9] http://www.epa.gov/oms/technology/research/how-it-works.htm (2011, Richard Matthews). [10] http://en.wikipedia.org/wiki/Rare_earth_elements. [11] Lunn, J. (2006-10-03). Great western minerals. London. http://www.gwmg.ca/pdf/Insinger_Report.pdf.

Retrieved 2008-03-18. [12] http://en.wikipedia.org/w/index.php?title=File:Elemental_abundances.svg&page=1. [13] Choruscars.com. (PDF) . Retrieved on 2012-04-18. [14] Haxel, G; J. Hedrick; J. Orris (2002). "Rare earth elements critical resources for high technology" (PDF).

USGS Fact Sheet: 087 ‐02 (Resto http://pubs.usgs.gov/fs/2002/fs087-02/fs087-02.pdf.

[15] Cox, C (2008). "Rare earth innovation: the silent shift to china". Herndon, VA, USA: The Anchor House Inc. http://theanchorhouse.com/2008/03. Retrieved cited 2008-03-18.

[16] G, Nishiyama. "Japan urges China to ease rare metals supply." 8 November 2007. Reuters Latest News. 10 March 2008 Reuters.com.

[17] http://csis.org/files/publication/101005_DIIG_Current_Issues_no22_Rare_earth_elements.pdf [18] http://www.hitachi.com/rd/research/hrl/battery_01.html. [19] Environmental impact of hybrid car battery. (2008). Retrieved December 09, 2009 from Hybridcars.com. [20] Gelani, S; M. Morano (1980). "Congenital abnormalities in nickel poisoning in chick embryos" (PDF).

Archives of Environmental Contamination and Toxicology (Newark, NJ, USA: Springer New York) 9 (1): 17–22. PMID 7369783. http://www.springerlink.com/content/x37h8256j6g27g84/fulltext.pdf. Retrieved 2008-12-09.

[21] http://en.wikipedia.org/wiki/Rechargeable_energy_storage_system. [22] http://en.wikipedia.org/wiki/Compressed_natural_gas. [23] http://www.autofocusasia.com/engine_chassis_systems/hybrid_and_fuelcell.htm. [24] http://www.thegreenmarketoracle.com/2011/12/ev-sales-predictions-in-us.html.

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ADAPTIVE ROBUST CONTROL APPLICABLE ON VARIABLE PUMPS

Daniel Vasile BANYAI1, Ioan-Lucian MARCU2 1 Technical University of Cluj-Napoca, daniel.banyai@termo.utcluj.ro 2 Technical University of Cluj-Napoca, lucian.marcu@termo.utcluj.ro

Abstract: The focus of the paper is on the nonlinear model based control of systems with unknown parameters and uncertain nonlinearities. The objective is to maximize the achievable performance of a controlled system and to obtain accurate parameter estimates. This is achieved by integrating the excellent output tracking performance achieved by the direct adaptive robust control with the good parameter estimation process of indirect adaptive designs. The paper contains a brief description of the nonlinear control algorithm and concludes with the results that demonstrate the high quality of the nonlinear controler

Keywords: nonlinear system, nonlinear control, uncertain nonlinearities.

1. Introduction

Essential trends, manifested today in hydraulic machines construction are those of flexibility and automation, meaning to increase their level of intelligence and adaptation to possible disturbances. [1]

Variable displacement pumps allow easy control of system parameters (pressure, flow, power, or combinations between them). Their technical characteristics make them become the best option for most applications from machine tools to mobile devices. [1]

Companies with a tradition in manufacturing pumps and motors with axial piston and variable displacement, produce this machineries for high automation systems (Rexroth, Bosch, Vickers, Parker.) the existing data in the literature on constructive solutions are few.

The biggest producers of hydraulic machines are opting for mechano-hydraulic control structures, that allow their use in circuits regulating pressure, flow and power independently one of another, each parameter control requiring a different type of constructive control structure .

For many years, the research in control of hydraulic machines, was focused on linear control, this was mostly due to the simplicity and ease of implementation of these methods.

Besides the nonlinear nature of the dynamic behavior, hydraulic systems have a lot of parametric uncertainties, which are found in variations of load and variations of hydraulic parameters such as modulus of elasticity. Uncertainties related to the nonlinearities are favored by: external disturbances, leakage flow, unmatched friction, etc. For these reasons, most often for nonlinear systems best control structure is a nonlinear one.

In this paper is developed an algorithm for the analysis of nonlinear systems, which integrates Direct Adaptive Robust Control and Indirect Adaptive Robust Control (D. / I.A.R.C.).

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2. Nonlinear control algorithm

Functional diagram of the system that is intended to be controlled by two nonlinear methods is presented in Figure 1.

Below is presented a schematic diagram for automatic control system proposed for implementation in a research program [1]. The system contains the following components: 1 - variable displacement pump with axial pistons; 2 - linear hydraulic motor needed to change the angular position of the piston block holder, so modify the flow of the pump; 3 – proportional directional valve, that control the position of the linear motor, 4 - pressure sensors; 5 – diaphragm, needed to measure the flow rate of the pump; 6 – electronic circuits with the following attributes: calculate the pressure drop on the diaphragm, then determine the flow, and then with the signal from a pressure sensor and the signal that represents the flow is obtained the hydraulic power generated by the pump; 7 - electronic comparator, designed to find the error between programmed and actual value of the adjusted parameter (pressure, flow, power); 8 – electronic controller, used to compensate the errors and gives the command signal for the proportional valve; 9 - switches whose state determines the control structure; 10 – fixed displacement pump, provides the necessary flow for positioning hydraulic motor; this flow can be taken from the adjustable pump’s flow, in this case the auxiliary pump is no longer required; 11 – relief valve, protects the system to not exceed the permissible pressure in hydraulic components. Thus without change in pump construction, this can be integrated into any control circuit for adjustable hydraulic machines, by simply actuation of an electrical switch.

Figure 1 Functional diagram of the investigated system

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Mechanical equilibrium equation of the linear motor is:

( )

( )

2 2

3 4 2

2

, , ,4

p m A a B am m m m m

s m m

m Rm x A p A p F k x C C x xa

d R p f t x xa

ωα

π

⋅ ⋅⋅ = ⋅ − ⋅ ⋅ + + ⋅ − + + ⋅ −

⋅ ⋅− ⋅ +

(1)

where ( )mm xxtf ,,~ is the error that incorporates external disturbances and friction forces non modelled.

the notations have the following meanings:

.

Ap − the temporal derivative of the pressure function, pA, in the large chamber of the linear hydraulic

motor; .

Bp − the temporal derivative of the pressure function, pB, in the small chamber of the linear hydraulic motor; pA – the pressure in the large chamber of the linear hydraulic motor; pB – the pressure in the small chamber of the linear hydraulic motor; pT –tank pressure, (pT=0); pc – the pressure between the pump and control valve; ps – load pressure; EU – elasticity modulus; VA – the volume of oil under pressure pA; VB – the volume of oil under pressure pB; VT – (dead) volume in the supply circuit of the linear motor, (connecting pipes volume); QA – flow rate that enters or is discharged from the large chamber of the positioning hydraulic motor; QB – the flow rate that enters or is discharged from the small chamber of the positioning hydraulic motor; A – the piston area (rodless); xm – linear position of the hydraulic motor; cLG – leakage flow coefficient dependent of speed; cLP – leakage flow coefficient dependent of pressure; α – piston surface ratio; αQ – flow rate coefficient; dv – proportional valve diameter; xv – linear position of the proportional valve; ρ – oil density; Tv – time constant for control valve; Kv – the gain of control valve; mp – linear motor piston mass; Fam – preload force of the spring in the linear motor; km – spring stiffness; c3 ; c4 – viscous damping coefficient; m – piston and rod of the variable pump’s, reduced mass; ω – angular velocity of the pump‘s piston holder; R – pump‘s pistons placement radius; a – tilting radius of the variable pump; d – pump’s pistons diameter.

Continuity equations are:

3

, 0;

, 0v v C A v

A

v v A v

k x p p xQ g

k x p x

⋅ ⋅ − ≥= =⋅ ⋅ <

(2)

4

, 0.

, 0v v B v

B

v v C B v

k x p xQ g

k x p p x

⋅ ⋅ ≥= =⋅ ⋅ − <

(3)

The equations that that show the forming of the pressure in the linear motor are:

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( )( ), , , ;UA A m A A B S T

T m

Ep Q A x Q p p p pV A x

= − ⋅ ++ ⋅

(4)

( ) ( )( ), , , ,UB B a m B A B S T

T a m

Ep Q A x Q p p p pV A L x

αα

= ⋅ − + ⋅ ⋅ −+ ⋅ −

(5)

where ,A BQ Q is the modelling error for flow equations.

Are defined the following variables in state space:

[ ] [ ]1 2 3 4, , , , , , .T Tm m A Bx x x x x x x p p= =

(6)

Considering xd(t) the desired position of the hydraulic differential motor, it seeks to obtain an input u, so that the size of output y=x1, to be as close as possible to the ordered value, despite various uncertainties of the model.

The system is subjected to parametric uncertainties due to the variation of the elasticity modulus, friction and damping, and the nominal value of the modelling errors (d, dn).

The equations system with input size u = xv in state space becomes:

(7)

For simplicity, we have considered only modulus Eu, and the nominal value of the modelling error d, dn. With the remaining parameters can do the same, if necessary.

It defines the following set of unknown parameters:

[ ]1 2, ;Tλ λ λ= (8)

1 ndλ = , 2 .uEλ = (9)

With this system described in state space can be linearized according to λ as follows:

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(10)

Uncertain parameters and uncertain nonlinearities satisfy the following: min max: ;θλ λ λ λ λ∈Ω = < < (11)

( ) ( )1 2 1 2, , , , ;dd t x x x x tδ≤ ⋅ (12)

( ) ( )3 4 3 4, , , , , , ; : , ,ii C T Q C TQ x x p p x x p p i A Bδ≤ (13)

where: , ,

A Bd Q Qδ δ δ - known and:

[ ]min 1min 2min, ;Tλ λ λ= (14)

[ ]max 1max 2max, ,Tλ λ λ= (15)

Are made the following notations: ~λ is the estimated error of λ ;

^λ - estimation of λ .

~ ^.λ λ λ= − (16)

Define the following discontinuous projections:

^

^

max^

min

0, 0;

( ) 0, 0;.

i

i i i

ii i i

i

daca si

proj daca siλ

λ λ

λ λ

= • >

• = = • <•

(17)

And the saturation function: ( ) 0 ;

Msat Sλ τ τΓ = Γ (18)

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1, ;

.

M

oM

M

dacaS

daca

τ λ

λ τ λτ

Γ ≤= Γ >Γ

(19)

It uses an adaptation law given by:

( )( )^,

M

proj satλ λ

λ τ= Γ

(20)

where: 0>Γ is a diagonal matrix;

τ – adapting function;

Mλ

– upper limit of the adaptation rate.

It is known that for τ∀ the projection used in equation (20) guarantees:

( ) ^ ^ ^

1 min max: ;P λλ λ λ λ λ∈Ω = ≤ ≤

(21)

( ) ( )( ) ( )^

~1 1

2 0;M M

T

P proj sat satλ λ λ

λ τ τ− − Γ Γ −Γ Γ ≤

(22)

( )^

3 .MP λ λ≤

(23)

Are defined the following functions:

( )1 1 ;dz x x t= − (24)

2 1 1 1 2 2 .eqz z k z x x= + ⋅ = − (25)

Controller design

Nonlinear controller design requires three steps:

Step 1

Is chosen a virtual control law given by the relations:

( )1 1 1 1 1, ;a Sx tα α α= + (26)

1 ;a dxα = (27)

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1 1 1 1 1,S Sk zα = − (28)

where 11Sk is gain factor of the positive feedback.

Step 2

The second equation of the system (10):

2 2 3 2 2;TCx b x φ λ− = + + ∆ (29)

2 ;p

Abm

= (30)

( )( )2 1 3 4 2 ;Ta amA F k C C kφ α= ⋅ + + − (31)

[ ]1 2 .Cλ λ λ= (32) Is chosen the adjustment law for x3:

^

2 2 2 2, , ;C a Sx tα λ α α = +

(33)

^

2 1 1 1 2 1 1 2 12

1 ;ˆT

Ca S S d dk x k x x zb

α ϕ λ = ⋅ + ⋅ + − − (34)

^

22 22

1 .ˆa bα λ= − ⋅

(35)

Step 3

At this step is defined the desired position xv of the valve, that is considered the input of the system.

3 3 3 ;TCx b u φ λ= + (36)

( )3ˆ, , ;C a su x t u uθ = + (37)

;B aAp

A B

Q Ad AF uV V

α⋅ ⋅⋅= + = (38)

3 4.p

VV a V

A B

Fx g A k g A k

V Vα=

⋅ ⋅ ⋅ ⋅ ⋅+

(39)

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3. Results and Conclusions

Was analyzed the behavior of the system like response to step command for pressure, flow and power. When adjusting the pressure the control step represents the input signal corresponds to a variation in load pressure from 0 to 200 bar, (Fig. 2a). When setting the flow, the control step representing the input signal corresponds to a variation in flow from 0 to 30 l/min, (Fig. 2b). In control of the power the version the step control that represents the input signal corresponds to a change in power in 0-5 kW, (Fig. 2c).

a)

b)

Figure 2 Dynamic behaviour of the system (Nonlinear Control)

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The controller presented in this paper have a good potential to use it in electro-hydraulic control systems with variable displacement pumps, it can get both good dynamic behaviour and a more precise estimate of the system parameters, the performance of which are difficult to reach for a nonlinear systems with regulators and classical control strategies.

Axial piston machines with variable displacement and electro-hydraulic control system allow a complete automation, compatible with the operating ciclograms of the complex equipments by interfacing with a PLC or process computer.

REFERENCES

[1] BANYAI D., New methods in synthesis of hydraulic machines with variable displacement and electro-hydraulic adjustment, PhD Thesis, Technical University of Cluj-Napoca, Romania, 2011.

[2] Virvalo T., Comparison of Tracking Controllers of Hydraulic Cylinder Drive by Simulations, Service Robotics and Mechatronics, Part 4, p. 55-60, 2010.

[3] Wang A., Yue B., Jiang K., Lin X., Non-linear Improvement on Hydraulic Pump and Motor Models Based on Parameter Optimization Algorithms, Lecture Notes in Computer Science, Artificial Intelligence and Computational Intelligence, Vol. 6320 p. 16-23, 2010.

[4] Wang Y., Schinkel M., Hunt K.J., PID and PID-like Controller Design by Pole Assignment within D-stable Regions, Centre for Systems and Control, Dept. of Mechanical Engineering, James Watt Building, University of Glasgow, Glasgow, G12 8QQ, 2001.

[5] Yu H., Feng Z., Wang X., Nonlinear Control for a Class of Hydraulic Servo-System, Journal of Hejiang University Science, Nr. 5(11), p. 1413-1417, 2003.

[6] Yao B., Bu F., Adaptiv Robust Motion Control of Control of Single-Rod Hydraulic Actuators: Theory and Experiments, IEEE/ASME Transactions on Mechatronics, Vol. 5, Nr. 1, p. 71-91, martie 2000.

[7] Yuzev A., Partial Asymptotic Stabilization of Nonlinear Distributed Parameter Systems, Automatica, Nr. 41, p. 1-10, 2005.

[8] Zheng D., Hoo K.A., Poovoso M.J., Finite Dimensional Modeling and Control of Distributed Parameter Ssystems, Proceeding of the American Control Conference, p. 4377-4382, 2002.

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ASSISTED OPTIMIZATION OF THE HYDRAULIC CYLINDER BY USING

THE ROOTS LOCUS CHARACTERISTICS AND LABVIEW INSTRUMENTATION

Prof.univ.Ph.D.Eng.Adrian Olaru1 and Ph.D.Eng.Serban Olaru2

1University Politehnica of Bucharest Romania 2RomSYS Mechatronics Company

Abstract

In the optimisation stage of the systems one of the more important step is the optimisation of the dynamic behavior of all elements with priority the elements what have the slow frequency, like motors. The paper try to show how will be possible to optimise very easily the dynamic behavior of hydraulic cylinder, using LabVIEW propre instrumentation, roots locus characteristics and the application of the transfer functions theory. By appling the virtual LabVIEW instrumentation is possible to choose on-line the optimal values for each constructive and functional parameters of the hydraulic cylinder to obtain one good dynamic answer: maximal acceleration without vibration, minimum answer time and maximal precision. The precizion-stability problem is non compatible problem that will impose to use the Extenics theory and assisted on-line research. The paper presents some of the more important used transfer functions in the assisted analyse of the elements and systems and some practical results of the assisted optimisation and the study case of the hydraulic cylinder. The future research will be show the optimal choose inside of the precision- stability field of the constructive and functional parameters by using the results of the Extenics theory.

1. Introduction

The transfer functions theory applied to the elements and the systems using the LabVIEW non linear components assure one very easily mode of the modeling, simulation and validation of the elements and systems, finally to obtain by sinthesys one integrated and intelligent system. Now, in the world, this theory and virtual LabVIEW instrumentation isn’t applied to optimise the systems, perhaps of the dificulties to find the corespondent validated transfer functions for each component of the system, or some complex transfer functions what assures one minimum errors of validation. In the paper will be presented one virtual LabVIEW propre library for the assisted research of the electrical and hydralic elements and systems with many results what will be possible to use in the curently research.

2. Transfer functions theory The created virtual LabVIEW instrument library contents one specify elementar transfer function for each components of the electrical, mechanical, hydraulic or complex systems. With these elementar transfer functions will be possible to exted the library with many others more complex, like for exemple PT6 –proportional- inertial system with six inertial order by serial link of three elementar transfer functions PT2, or PD2T2- proportional- derivative and inertial of the second order by serial link of two PDT1, and s.o. In the table 1 you can see more of these complex transfer functions using the elementar functions and in the table 2 some of the more important transfer functions used in many modeling and simulations of the elements and systems [1], [2], [3], [4], [5]. With the elementar transfer functions theory and by using the non linear functions from LabVIEW library is possible to simulate any complex servo driving systems. The propposed method contents in two ways of optimization: the first is to choose all constructive and functional parameters of the components by on-line work of the propre virtual complex LabVIEW system to obtain the desired dynamic results- perhaps one minimum acceleration time without oscilations, or one output characteristics without vibrations indifferent of the acceleration time, or one Fourier spectrum to the higher field, etc[6], [7], [8], [9]. All these situation is possible to show by on-line work of the VI; the second will be to introduce in to the initial schema of many corrections, choose the regulator and controllers parameters, or to introduce complex control laws. These will be possible very easy by using the transfer functions, becouse it is know the action to the dynamic behavior of each of them.

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For example to atenuate the intertial action of the second order it is indicated to introduce in to the initial schema of one control law of the type PD2- proportional derivative of the second order, what control the inertial term, the damper term and the stifness term of the system. By using this control law was possible to minimase the acceleration time and to obtain one answer without any vibrations, like you can see forward in the paper. Table 1. Some expressions and virtual LabVIEW instruments of transfer functions

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Table 2. Some models of transfer functions and his characteristics, mathematical and physical models

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In the modeling of the elements and systems one more important thing is to aproximate better the real function of the systems. For that will be necessary the folling steps: write the mathematical model and to aplly the Laplace transformation; determine the transfer elementar function of each component; simulation of the elements and compare the results with the real characteristics of the researched elements, in this case LHM (linear hydraulic motor); the validation of the model or changing them to obtain one minimum errors between the model and the real one. After these assisted research will be possible to optimise the results only by numerical simulation becouse the mathematical model was validated and completed with some new coefficients what results from the validation step.

3. The cylinder’s mathematical model and the experimental validation [10, 11, 12, 13, 14]

The applied mathematical model, in this case for the hydraulic cylinder, was developed in one complex matrix form to take in to the research all input and output data. The general matrix form of one mathematical model with two output and two input data is:

=

=2221

1211

2

1

2

1

)()()()(

)]([HHHH

sxsxsxsx

sH

i

i

e

e

(1)

The LHM is one inertial of the second order type of the transfer function like this:

kUxdt

dxTTh

dtdx

TT eee =+++ )( 212

2

21 (2)

Finally, the matrix form in the state space will be:

)(0

)(110

212

1

21

21

212

1 tUTTk

xx

TTTTh

TTxx

+

+

−−=

′′

(3)

( )

=

2

101xx

Y (4)

General for of the state space relation will be: ( ) [ ]( ) [ ]( ))()()( tuBtxAtx +=′ (5)

( ) [ ]( ) [ ]( ))()()( tuDtxCty +=

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After application of the Laplace transformation, the output will be:

)()(][][)( 10

1 sDUsBUAsICxAsICsY TT +−+−= −− (6) where:

.)1(

)1(

;)1(2)(;

)1(2

21

1

21

1

2121

1

21

mmfu

fu

mmfu

mm

mmfu

bacAQcA

kU

bacA

bEcAma

TThbacA

EcAm

TT

+−

−=

+−

+=+

+−=

(7)

and where: Q is the flow 20-100 [cm3/s]; A– active motor area 50-80 [cm2]; c- active movement 30-40 [cm] ; am- proportional gradient of loss flow with pressure 0.2-0.7[cm5/daNs]; ∆p- loss pressure 4-6 [daN/cm2]; V – hydraulic volume of the motor 500- 1000 [cm3]; m- reduced mass on the motor axis 0.1-0.6 [daNs2/cm]; bm- gradient of loss forces proportional with velocity 0.8-1.8 [daNs/cm]; F – resisting forces 10-30[daN]. Relation (6) is the real output and will be change in to the follwing form, if the all input data will be step type:

s

UDs

UBAsIcsx

AsIcsY TT +−+−= −− 101 ][][)( (8)

Finally, after changes of the product in the sume and after applied the inverse Laplace transformation the relation for the velocity of the hydraulic cylinder will be: y1=k(1/psi2)*q*(1-(1/e^(omega*psi*dt))*(1/psi2)*sin(omega*psi2*dt+atan(psi2/psi)))-(F+a0)*(am/b0)*(1-1/e^(b0*dt/ (am*m))) a00= k*q*(1/psi2)-((F+a0)*(am/b0)) a0=p*A1 b0=((A1**2)*0.86)+am*bm b1=M*am+(A1*c*bm/(30000)) (9) b2=M*A1*c/(30000) b00=A1*0.86 k=b00/b0 psi=b1/(2*sqrt(b2*b0)) omega=sqrt(b0/b2) psi2=sqrt(1-psi^2) The results after the numerical simulation step and the experimental research of the cylinder were obtained the characteristics from the fig.1.

Fig.1. Validation of the LHM mathematical model- comparative analyze of the experimental and simulation results

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4. Assisted optimisation of the hydraulic cylinder using the propre LabVIEW

instrumentation The assisted optimisation used the validated mathematical model of the cylinder and by changing some constructive or functional parameters. In the figs.2-4 were changed the flow loss and the force gradients, am, bm, the active area A1, the movement of the motor stem, c.

Fig.2. Front panel of the virtual LabVIEW LHM instrument for the comparative analyze, when was changed the flow and resistance force gradients, am, bm

Fig.3. Front panel of the virtual LabVIEW LHM instrument for the comparative analyze, when was changed the active area, A1

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Fig.4. Front panel of the virtual LabVIEW LHM instrument for the comparative analyze, when was changed the active area and the movements of motor steam, A1, c

Analyzing the optimization applied to the hydraulic cylinder LabVIEW proper VI results the following remarks: by increase the flow and force gradients were obtained some transfer of the poles in the plane poles- zeros to the stability field, velocity were obtained without any vibrations, fig.2; by increase the active area was obtained the displacement of the poles outside of the precision – stability field but one magnification of the answer with decrease of the acceleration time with the effect in to the increase of the movement precision, fig.3; by decrease of the active movement of the LHM steam was obtained one magnification of the velocity output with the same acceleration time with the second example, but without any vibrations of the velocity output, fig.4. By this method is possible to choose the constructive or functional values of the hydraulic cylinder to obtain one good dynamic behavior answer to obtain one good precision, or stability, or better solving the compromise precision- stability problem. Without on-line work of the proper LabVIEW VI-s is not possible to obtain these results. The constraints of the precision- stability field is shown in fig.5. To optimize the dynamic behavior on used the roots locus method are shown in the paper, figs.6-8.

Fig.5. The constraints of the precision-stability field

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Fig.6. Some results of the roots locus after the numerical simulation when were changed in the functional field: active area and force and flow gradients

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Fig.7. Some results of the roots locus when were changed flow gradient, force’s gradient and active area

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Fig.8. Some results when were changed flow gradient, force’s gradient, active area and displacement

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The optimal answer of the hydraulic cylinder about the precision- stability criteria using the roots locus method is the case a and c from the fig.7. The constraints are the followings:

12

12

12

12

nnn

ppp

ttt

ννν

νννξξξννν

≤≤

≤≤≤≤≤≤

10)

and the conditions will result after the on-line numerical simulation:

12

12

12

12

cccbbbaaa

AAA

mmm

mmm

≤≤≤≤≤≤

≤≤

(11)

In the study case the goals were:

9143

55318.07.0

6141

≤≤

≤≤≤≤≤≤

n

p

t

ν

νξν

(12)

and the on-line choosing the conditions:

[cm2] [cm5/daNs] [daNs/cm] (13) [cm]

5. Conclusions The assisted research with the LabVIEW instrumentation open the way to optimize the dynamic behavior of the elements and systems. In the study case was researched one hydraulic cylinder for what were imposed some goals (constraints) linked to the application. The complex problem of all dynamic behavior of the elements and systems is to optimal solve the contradiction problem between the precision and stability, because if the precision increase, the stability decrease. The optimization method what used to solve this problem was to define some constraints of the precision-stability field and to try put the roots locus inside of this field. After that easily could see the values of the functional and constructive parameters what solve the problem. The research was easily solved by on-line numerical simulation by using the virtual LabVIEW instrumentation. In the future will be applied the Extenics new complex mathematical method and the assisted LabVIEW instrumentation dedicated to this subject, optimal solves the contradictory problem. 6. References [1] Olaru, A. Dynamic of industrial Robots- Modeling dynamic behavior of the elements and the systems utilized in construction of the industrial robots, Bren Edition 2001, ISBN 973-8143-65-9. [2] Oprean, A., Olaru A., Ioanid, P. Computer aided research for dynamic behavior of forging manipulators orientation modulus, IMEC, Manufacturing Engineering 2000 and Beyond, Freud, SUA,1996, pag345-352, 1996. [3] Oprean, A., Olaru, A. Theoretical and experimental analyze of position and velocity at articulated arm industrial robot SISOM 2001 Bucharest. [4] Olaru, A. Theoretical and experimental cinematic research of industrial robots, The 12th International DAAM Symposium “ Intelligent Manufacturing & Automation: Focus on Precision Engineering ” 24-27th October 2001, Jena, Germany.

5040209183

3529583

≤≤≤≤

≤≤≤≤

cb

aA

m

m

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[5] Olaru, A., Staicu, St. Theoretical and experimental research dynamic behavior of industrial robots University “Politehnica” Bucharest Publishing House 2001. [6] Olaru Serban , Oprean Aurel, Olaru Adrian, Assisted research of the rheological dampers with LabVIEWinstrumentation, The 1st European DAAAM International Young Researchers´ and Scientists´ Conference, 24-27th October 2007, University of Zadar, Zadar, Croatia, 2007. [7] Olaru, A., Olaru, S. Research Of The Industrial Robot Dynamic Behavior With Labview Instrumentation, OPTIROB Proceedings, Romania, 2007. [8] Oprean Aurel, Olaru Serban, Olaru Adrian. Some Contributions Of The Modeling And Simulation Of The Magnetorheological Dampers, OPTIROB Proceedings, Romania, 2007. [9] Adrian Olaru, Paune Danut, Adrian Ghionea, Serban Olaru, Peli Alexandru Research with LabVIEW instrumentation of the robot trajectory errors, OPTIROB Proceedings, Romania, 2007. [10] Adrian Olaru, Serban Olaru, Assisted optimization of the electro-hydraulic servo driving with LabVIEW instrumentation, The 6th Iranian Aerospace Society Conference- Feb. 2007-K.N.Toosi University of Technology, Teheran, Iran, 2007. [11] Olaru Adrian, Olaru Serban, Assisted dynamic behavior optimization of the robots elements and systems with the virtual instrumentation, 15th Annual (International) Mechanical Engineering Conference May 2007, Amirkabir University of Technology, Tehran, Iran, 2007. [12] Oprean Aurel, Olaru Serban, Olaru Adrian, Some contributions on the magnetorheological damper assisted research , OPROTEH2007, Bacau, Romania, 2007. [13] Serban Olaru, Adrian Olaru, Assisted research of the Bouc-Wen damper new mathematical model with LabVIEW instrumentation, AERO2008, Teheran, Iran, 2008. [14] Olaru, A. & Olaru, S. -Research of the global dynamic compliance and the viscose global dynamic damper coefficient of the industrial robot- DAAAM "Intelligent Manufacturing & Automation: Focus on Mechatronics & Robotics" 08-11th November 2006, Viena, Austria. [15] Olaru Adrian, Olaru Serban- Research of the industrial robot fourier spectrum with LabVIEW instrumentation – First Regional Conference of Mechanical Engineering Islamic Azad University, Majlessi New Town Branch December 13th, 2006. [16] Adrian Olaru -Assisted research of the industrial robots global dynamic compliance with LabVIEW instrumentation- Proceedings ICMaS Published by Editura Academiei Romane, University POLITEHNICA of Bucharest, Romania, 26 - 27 October, 2006. [17] Olaru, A. Assisted research with virtual LabVIEW instrumentation of the industrial robots vibration behavior, Acta Mechannica Slovaca, Vishe Ruzbachy, Slovacia 2004. [18] Olaru A., Olaru S., Peli Al., Paune D. 3D complex trajectory by using the robots and perirobots components, 9th International Conference on Automation/ Robotics in Theory and Practice, Slovakia 2008, p.431-444. [19] Olaru, A., Olaru S., Ciupitu, L. Assisted research of the neural network by bach propagation algorithm, OPTIROB 2010 International Conference, Calimanesti, Romania, The RPS Singapore Book, pp.194-200 , 2010. [20] Olaru, A., Olaru, S., Paune D., Ghionea A. Assisted research of the neural network, OPTIROB 2010 International Conference, Calimanesti, Romania, The RPS Singapore Book, pp.189-194 , 2010. [21] Blelloch, G., & Rosenberg, C.R. “Network learning on the Connection Machine” Proc. of the Tenth International Joint Conference on Artificial Intelligence. Dunno, pp. 323-326, 1987. [22] Cybenko, G. Approximation by superpositions of sigmoid function, Mathematics of Control, Signals, and Systems, vol.2., pp.303–314, 1989 [23] Elman, J.L.Finding structure in time, Cognitive Science, 14, pp.179-211, 1990. [24] Fukushima, K. Cognitron: A self- organizing multilayered neural network, Biological Cybernetics, 20, pp.121-136,1975. [25] Hartman, E.J., Keeler, J.D.,&Kowalski, J.M. Layered neural network with Gaussian hidden units as universal approximations, Neural Computation, 2(2), pp.210-215, 1990. [26] Hopfield, J.J. Neural networks and physical systems with emergent collective computational abilities, Proc.of the National Academy of Sciences, 81, pp.3088-3092, 1984. [27] Lippmann, R.P. An introduction to computing with neural nets, IEEE Transactions on Acoustic, Speech, and Signal Processing, 2(4), pp.4-22, 1987. [28] Minsky, M., & Papert, S. Perceptron: An Introduction to Computational Geometry, The MIT Press, 1969. [29] Dimith, H., Beale M.& Hagan M.: Neural Network ToolboxTM 6- User Guide, The MathWorks, Inc. 3 Apple Hill Drive Natick, MA 01760-2098, USA. [30] Cai Wen: The Extension Set and Non- compatible Problems, Editor Chien Weizang, Advances Mathematics and Mechanics in China (Vol.2), International Academic Publisher, 1990, p. 1-21. [31] Cai Wen: Matter-element Models and Their Applications, Beijing: Science and Technology Document Publishing House, (1994).

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DIVISIONS OR SUMMATIVE HYDRAULIC FLOW STANDARD

Victor BALASOIU1, Ilarie BORDEASU1

1 Universitatea Politehnica din Timisoara, balasoiu89@yahoo.com; 1 Universitatea Politehnica din Timisoara, ilarica59@gmail.com; Abstract After a presentation of the concept of hydraulic flow divider that element to synchronize the movement of two motors hydraulic flow divider details the 1: 1. Based on an equivalent hydraulic scheme is acriu hydraulic balance equations for hydraulic divider 1:1 made in Timisoara Hydraulic Machinery Department. Based on the analysis of the static behavior of the flow divider are highlight factors that contribute to increased precision division. It shows that the error of division is the main parameter performance of a flow divider. Keywords: flow divider, flow system, drawer divider, error of division, timing displacement, hydraulic proportional dividers 1.Introduction. Flow dividers are hydraulic elements for division or summation of the working fluid flows predetermined proportions[1]. Flow dividers constant ratio of debt divided their use schemes are operated under different timing of construction equipment (loaders, excavators), presses, etc. Whatever the particular constructive split drawer partitions (fig.1, fig.2) is based on automatic insertion of an a dditional hydraulic resistance branchless loaded, which reduces the flowin this branch by increasing the flow of overloaded branch (F2>F1), ensuring the final displacement synchronized hydraulic motor (3) and (4) (fig.1, 2) [1]. On flow dividers have made clear that, in addition to control flow division1: 1, the device has the ability to maintain this relationship, regardless ofload variation on the two branches control. Flow divider resulted from bringing together two-wayflow, which caused loss of compression springs. Comparison(2) (drawer divider) is in equilibrium under the action of pressure p3 and p4 (fig.7.36). In this mode comparator and final position regulation disturbances are caused by the difference of the two branches-two hydraulic motors variation tasks. Droselele regulatoartelor flow components were replaced with fixed resistors R1 and R2 and adjustable resistors R3 and R4 are determined by slots droselizare mobile element (fig.3.b). In fig. 3 are two variants of flow dividers: by dividing the aperturering (fig.3.a) and diaphragms embedded in the drawer divider (fig.3.b). Split flow with constant pressure, move the connector (1), by obruratoarele ring (6) and (7) (resistors R1 and R2- fig.3.a, b, fig.3.a) at droselele of adjustment (5) and (9) (resistors R3 andR4 - fig. 3.a, b) the drawer divider, for lines and leading to the two hydraulic motors. Rooms (15) and (16) are connected with pressure chambers(13) and (14), the compartment divider channels (10). Equal loads on both hydraulic motors, pressure in the chambers(15) and (16) are equal and hence drawer divider (10) will be in the middle position. To differences in taskt wo branches (fig.3) due to pressure differences, drawer divider (10) moves until it compensates the difference in pressure, so in leads I and II will be the same flow division error is shall not exceed∈= 𝑄𝑄1−𝑄𝑄2

𝑄𝑄0 =3%-4%.

Precision Hydraulics divisionis influenced by elasticity, compressibility fluid, displacement and deformation losses related pipelines. To decrease the influence of these factors is recommended that the divider to fit closer to the two hydraulic motors serviced.

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Fig.1 Fig.2

a)

b)

Fig.3. Flow divider 1:1.

a) resistance in the drawer edges, b) with drawer divider resistors 1. body divider, 2, 12. check valve, 3, 11.adjustment screw; 4, 5, 9. Input-Output section 6. sealing ring 7.section drawer divider 8.ring section 9.divider sleeve, 10.drawer divider;13, 14. Droselizare section; 15.16. control rooms drawer divider

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Flow dividers are used in different combinations of synchronous and asynchronous operation of the two hydraulic motors for synchronous operation within a meaning and asynchronous operation in reverse.Way valves (2) and (12) (fig.3.a and b) mounted flow divider allows rapid recirculation of the fluid in the opposite direction with out resistance about. Screws (3) and (11) limits the maximum opening of variable resistance, and stroke. 2. Error of division, factors which divide error Equal flow in both branches is determined by an equalization of pressure drop fixed resistors R1 and R2, and R3 and R4 adjustable, ie (fig, 1, 2): respectively:

)pp()pp(p 403034 −=−=∆ (1) respectively: ∆p12 = (p3 - p1) = (p4 - p2 ) (2) Drawer divider is under the action of fluid pressure p1 and p2 control rooms Fh1 and Fh2 hydrodynamic forces the liquid flow passing through windows R3 and R4, and the friction forces between the gate and body Ffr divider. Axial component values of hydrodynamic forces (Fh1 = Fh2) are proportional to fluid flow passing through sections droselizare. Equations of continuity and steady flow stationary mobile element are:

( )

±−=−π

−ρ

−π=−ρ

=

−ρ

+π=−ρ

=

+=

F

fr2h1h43

2S

24S0SS2d4021d2

13S0SS2d3011d1

21

FF)pp(4

D

)pp(2)YY(DC)pp(2fCQ

)pp(2YYDC)pp(2fCQ

QQQ

(3)

Here were noted: Cd1 and Cd2, flow coefficients corresponding hydraulic resistances R1 and R2, R3 and R4 respectively; YS0 - initial opening slots for droselizare symmetrical position in the body drawer divider, YS - drawer movement relative to the position initiation. Hydrodynamic forces are calculated momentum relations:

fr24S0SS2d

13S0SS2d43

2S

F)pp()YY(DC2

)pp()YY(DC2)pp(4

D

+−−π−

−−+π=−π

(4)

under equilibrium conditions, Fh1= Fh2 , we have:

2S

fr43

DF4

ppπ

±=−

(5)

which shows that the error of dividing the flow depends on friction forces. For varying loads F1≠ F2, resulting p1≠ p2, and flow differences presence results in the appearance of axial components of hydrodynamic forces Fh1– Fh2 = Fh and get:

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p3 - p4 = 2S

fr2

S

h

DF4

DF4

π±

π (6)

and shows that the error of division of flow is determined by hydrodynamic forces and friction forces in the pair drawer - body divider. Synchronization error between the two engines is defined as:

0

21

QQQ −

=ε (7)

or written as:

M

12

M

2121 S

QS

QQvvv

∆=

−=−=∆ (8)

From the analysis of flow dividers, shows the following: - Error of division is the main parameter characterizing the performance of a flow divider; - Irrespective of the division, the annular diaphragm or diaphragms embedded in drawer partitions (fig.2, fig.3), reducing the error of division compensation is necessary pressure drop in system synchronization or reaction forces the drawer divider; - Synchronization of two hydraulic motors with the same section utile SM or the same displacement Vg useful MS, and under the same load conditions F1 = F2, involves using two equal resistors R1 = R2 = R on the two branches of the circuit; - Synchronization of two hydraulic motors different sizes and / or different loading conditions can be provided by using different resistors; - Error of divisionis directly affected by the presence of axial components of hydrodynamic forces, the forces of friction and internal leakage of fluid; - Reduction of the synchronization error is achieved by shorting the motor power sector through a properly sized resistors compensation; - Reduction of the synchronization error can be made by reducing the area of application of the pressure response and / or useful surface SM engines; - Appropriate technology drawer assembly - body divisor, ie a proper choice of games and surface quality for parts in direct contact, leading ultimately to reduce the error of division within the value ε = ± (3 ÷ 5) % recommended of the literature specialized. 3. Conclusions Following requests perturbations of differential synchronization is adjusted via flow dividers placed on the water both on entry and exit hydraulic motors. Engine speeds equality movement is approximate, depending on timing precision flow controllers integrated indicative of flow dividers and their working conditions. Flow dividers constant ratio of debt divided inb find their use of various schemes operated machines. Regardless of particulaitatile constructive split drawer partitions (Fig.3), is based on automatic introduction of additional hydraulic resistance less busy branch, which reduces flow resistance in this branch. To increase the flow of overloaded branch (F2> F1), ultimately providing simultaneous displacement hydraulic motors MH3 and MH4 (fig.2). Synchronization accuracy is influenced by the elasticity Hydraulics, fluid compressibility, volume loss and deformation of the connecting pipes. To decrease the influence of these factors it is recommended to mount divider closer to the two hydraulic motors serviced.

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Given that require flow sharing between two users may not be in the ratio 1: 1, but different, sometimes varying phase of work required proportional flow dividers. IHP Bucharest, made the first hydraulic proportional dividers variants [1, 3]. REFERENCES [1] Victor Balasoiu, Ion Cristian, IlareBordeasu, “Echipamentesisistemehidraulice de actionaresiautomatizare”, Vol I, Aparaturahidraulica, EdituraOrizonturiUniversitare, Timisoara, 2008 [2] VictorBalasoiu, Echipamentehidraulice deactionare, fundamente, echipamentesisisteme, fiabilitate, EdituraEurostampa, Timisoara , 2001. [3] Victor Balasoiu, Echipamentesisistemehidropneumatice de actionare, Vol II, partea I , II, LitografiaUniversitatiiTehnice, Timisoara, 1992 [4] I.Iu. Ciuprakov, Ghidroprivod I sredstvaghidroavtomatiki, Mosckva, Masinostroenia, 1979 [5] PetrinDrumea- Contributii la analiza si sintezaelementelor si instalatiilor de reglarweelectrohidraulice, Teza de doctorat, UniversitateaPolitehnicadin Bucuresti, 1998. [6] V. A. Hohlov – Electroghidravliveskiislediasciesistemi, Masinostroenie ,Mosckva, 1971, [7] *** The Procedings of the 6 th International Conference on Hydraulic Machinery and Hydrodinamics , Timisoara, oct 2000, Vol I, II, II. [8] *** Conferinta de MasiniHidraulice si Hidrodinamica , Timisoara, 1990 [9] V. Javgureanu, Actionarihidraulice si pneumaticeînmasini si sisteme de productie”. CursUniversitar, Editura UTM Chiúinu, 2011.460 p.

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THE INCREASING OF THE TRIBOLOGICAL PERFORMANCES OF THE FLUID POWER EQUIPMENTS

Ph. D. Eng. Corneliu CRISTESCU1, Prof. Ph.D.Eng. Iile FILIP2

Assoc. Prof. Ph.D.Eng. Alexandru RADULESCU2, Assoc. Prof. Ph.D.Eng. Sorin CANANAU2,

1Hydraulics & Pneumatics Research Institute-INOE 2000-IHP from Bucharest, ROMANIA, cristescu.ihp@fluidas.ro; 2 “POLITEHNICA”University of Bucharest, ROMANIA, s_cananau@yahoo.com; varrav2000@yahoo.com; filip@meca.omtr.pub.ro Abstract: The article presents a series of tribological researches regarding the increasing of the performances of fluid power equipments, developed in the Laboratory of Tribology and Lubrication Systems, within Hydraulics and Pneumatics Research Institute in Bucharest- INOE 2000-IHP, including some concrete results obtained. In particular, are presented, some researches on the tribological behavior of sealing systems of hydraulic cylinders, as well as several testing devices of some tribology couplings which are specific to hydraulic equipment. Keywords: tribology, hydraulics, testing laboratory, testing stand, lubrication systems, 1 Introduction Having over 50 years of experience in Fluid Power field, in the current research, besides the theoretical aspects needed to be clarified a series of specific aspects,, in the institute a particular attention has the experimental research, designed to confirm the theoretical research, or showing certain performance of the components or for the equipment which are investigated.. The main research directions in the activity of the institute are:

• hydrotronics, mechatronics and tribology; • green energies; • technological transfer.

Between the 10 research laboratories, which were developed in the institute, one of the most important laboratories is The Research Laboratory for Tribology and Lubrication Equipments, where were developed o series of research activities regarding the knowing the tribological behavior of the hydraulic elements and systems, in order to optimize the energetic efficiency of all hydraulic driving systems. It is meant for research in the general field of tribology, especially for the systems and equipments centralized lubrication, that are important for the security of technological systems. 2. The main direction of the tribological research In the Research Laboratory for Tribology and Lubrication Equipments, the main direction of the research activities, which are developed are:

1. The tribological research of the sealing systems from the hydraulic drive sistems, especially from the hydraulic and pneumatic cylinders:

2. The tribological investigation of the material couples with radial relative motion, from hydraulic drive systems (radial bearings, radial seals, radial joints, etc..), including hydrostatic radial bearings;

3. Tribological Research of the the material couples with relative frontal /axial motion, from the hydraulic drive systems (flat bearings, axial or frontal, front seals, etc..), Including hydrostatic thrust bearings;

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4. Tribological Research of the material couples with the relative translational motion, from

the hydraulic drive systems (axial couples, translational seals, and, also, the specific translational systems of the piston on cylinder;

5. Tribological research on classical, modern and modernized lubrication systems. 3. The tribological research of the sealing systems of the hydraulic cylinders

Hydraulic cylinders, which are basic components of hydraulic control and actuation systems, convert hydrostatic energy into mechanical energy, by achieving, in a certain time, a certain force, with a certain speed in a straight stroke and must ensure a proper dynamic behavior, The researches, regarding the tribological behavior of the sealing system of the hydraulic cylinders, were developed together the specialists from the University of Poitiers, Poitiers, France. Until now, were developed two steps:

1. Experimental research regarding experimental the determination of frictional forces that occur between the rods of hydraulic cylinders and their seals.;

2. Experimental research in order to measure the friction forces which appear in the pistons seal of the hydraulic cylinders.

3.1 Experimental researches for determining of the frictional forces from sealing of rod of hydraulic cylinders This are presented some aspects of conducting, within INOE 2000-IHP, of experimental research on the determination of frictional forces that occur between the rods of hydraulic cylinders and their seals. In the first part, are presented some specific elements of the experimental stand developed and in the second part are presented some graphical results. For experimental determination of frictional forces, occurring between the seals and hydraulic cylinder rod, was designed and developed a testing stand equipped with modern “on-line” system for measuring the evolution of the parameters of interest. The main unit of the test stand is the experimental device, which contains the investigated sealing and is mounted on the framework of the drive system Figure 1, where it can be seen both the dual sealing sleeve which contains the two gasket U shape, Figure 2, the pressure and temperature transducer, as well as the force transducer, Figure 3. A general view of the stand can seen in Figure 4, a, b.

Fig. 1: The experimental device

mounted on stand.

Fig.2 The pressure and temperature transducer.

Fig. 3 The force transducer.

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a): General view if the stand

b) The manual acting of the pump

Fig. 4: The general view of the testing stand

Some experimental graphical results for rod sealing To concretize the above mentioned, below will show some examples of complex graphics obtained for certain pressure and speed steps, which will reveal some interesting and instructive points. Thus, in Figure 5 si Figura 6, are represented the complex characteristic graphs for pressure steps values of 100 bar and 200 bar and theoretical 100 mm/s).

Fig. 5 The complex graphics for rod sealing at pressure of 100 bar.

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Fig. 6 The complex graphics for rod sealing at pressure of 200 bar.

3.2. Experimental research for measuring the friction forces which appear in the pistons seal of the hydraulic cylinders

The mobile/dynamic translation sealing are specific to the hydraulic cylinders, Figure 7a, where realize the sealing on the piston with diameter d, being in reciprocating translation motion on the stroke, in a fluid medium with the constant viscosity η and under pressure p. In Figure 7b, d is the piston diameter, S is the stroke, v and vr are velocities in the both senses

a)

b)

Fig. 7 Hidraulic cylinders piston sealing

For evaluating the friction forces from the piston seal of the hydraulic cylinders, there was designed and developed a special experimental device, which was conceived purposefully for working by mounting on an existing stand, which provides operational strokes for piston. The adopted technical solution was the replacement of the piston, with one new piston double sealed, which contains two spaces where are placed 2 U seal shape type seals, fixed with the wings facing one another. The pressure of working oil, sealed by the two gaskets tested, is created by using a hand pump, which has a pressure gauge to indicate directly the working pressure and, also, a local display pressure transducer.

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The experimental device, prezented in Figure 8, operates in vertical position and it needs the mounting of the rod of the experimental device on the mobile rod of the hydraulic cylinder from one existing Stand.. Figure 9 presents the pressure and temperature transducer and Figure 10 presents the force transducer, used to measure the friction forces.

Fig. 8: The experimental -device

mounted on stand. Fig. 9: The pressure and temperature transducer.

Fig. 10: The force transducer.

Also, the stand has others transducers as: stroke transducer, a digital thermometer for the ambient temperature and flow transducer. By means of special electric cables, all signals provided by transducers reach the acquisition board installed on the computer, and this one, based on specialized software, allows the capture, storage and processing of data.

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Some experimental graphical results for piston sealing To concretize the above mentioned, below will show some examples of complex graphics obtained for certain pressure and speed steps, which will reveal some interesting and instructive points. Thus, in Figure 11 si Figure 12, are represented the complex characteristic graphs for pressure steps values of 100 bar and 200 bar and theoretical 100 mm/s).

Fig. 11 The complex graphics for piston sealing at pressure of 100 bar.

Fig. 12 The complex graphics for piston sealing at pressure of 100 bar.

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4. The testing device for radial hydrostatic bearings and radial sealing systems

In the Research Laboratory for Tribology and Lubrication Equipments, there is an electro-mechanical-hydraulic testing device for radial hydrostatic bearings and radial sealing systems, which enables the development of research for industrial applications, regarding measuring of the friction couple/moment which appears in the working regimes of the machinery and equipments. This testing device is presented in the Figures 13, where it can see, also, the Hydraulic action scheme.

–Side view-

–Top view-

Hydraulic action scheme

Figure 13: The testing device for radial seals and radial hydrostatic bearings

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5. The testing device for frontal hydrostatic bearings and axial sealing systems,

A second device, also, an electro-mechanical-hydraulic device, which is in the Research Laboratory for Tribology and Lubrication Equipments, allows to develop the experimental researches of the axial/frontal hydrostatic bearings and frontal sealing systems, belonging from industrial applications. The testing device is presented in Figure 14.

The physical testing device

Hydraulic action scheme

Figure 14. The testing device for frontal seals and frontal hydrostatic bearings

6. The durability Testing of the translational seals systems from the hydraulic cylinders Other testing device is for durability testing for the transnational seals system from hydraulic cylinders, which is presented in the Figure 15.

The phisical testing device

The aquisition system

The design of testing device

The scheme of aquisition system

Figure 15: The testing device of seals durability

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7. Classical, modern and modernized lubrication systems

In the Tribology Laboratory was effectuated o lot of studies regarding the basic and modern lubrication systems used in the industrial equipments, in order to create new technical solution and for improve the used now on the old machineries. The laboratory has a number of functional panels, for the main systems of centralized lubrication, namely for volume dosing systems, Figure 16, progressive dosing systems, Figure 17, the lubrication systems with two lines, Figure 18, the recirculation system with electronic monitoring, Figure 19, and, also, the micro lubrication systems and spray lubrication systems.. These functional panels are used in training activities of our institute, which are developed with the industrial companies, in order to transfer the basic knowledge

Figure 16: The volumic dosing lubrication

systems,

Figure 17: The progressive dosing lubrication

systems

Figure 18: The lubrication systems with two

lines

Figure 19: The recirculation lubrication system

with electronic monitoring

These functional panels materializing, at small scale, the real lubrication systems of the machines and technological equipment from the industry, and can be used for testing for specific lubrication components, for the training activities in the lubrication field, and, also, for functional demonstrations of the main/based lubrication systems. 8. Conclusions The paper presents a series of tribological research which have developed in Tribology and Lubrication Systems from Hydraulics & Pneumatics Research Institute-INOE 2000-IHP, regarding the increasing of the performances of the fluid power equipments.

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• The paper presents, in detail, the measurement device and the stand for measuring

frictional forces in rod seals and in piston seals of hydraulic cylinders and there are shown graphic examples of their variation.

• Valid measurements of frictional forces are obtained in downward stroke, due to the phenomenon of natural alignment of the piston rod and the force transducer that eliminates the occurrence of additional jamming forces.

• It is shown that the three graphs for two consecutive cycles, which are almost identical, demonstrate repeatability of the process.

• In the paper are presented examples of complex graphical variation, for 100 bar and 200 bar, two examples for rod friction forces and two for piston friction forces.

• The measurement system, based on advanced transducers and electronic and computerized data processing, guarantees the accuracy of measurements performed on the stand.

The paper presents diferent researching devices for radial and frontal hydrostatic bearings and sealing systems, and, also, some classical, modern and modernized lubrication systems Finally, considering all the above, it can say that the Tribology and Lubication Systems Laboratory from INOE 2000-IHP has an important endowment and can develop interesting research works on tribology and lubrication industrial equipments. The development of large scale works, needs integrated research strengths, that can be achieved through cooperation between universities and institutes with expertise in the field, from different countries, which is posible only on one European research projects REFERENCES 1. Cristescu C., Drumea P., Dumitrescu C., The theoretical evaluation and experimental

measuring of the friction forces from the sealing of rod at the hydraulic cylinders, Proceedings of The 26-th international scientific conference- “65 years Faculty of Machine Technology”, Technical University Sofia, 13 – 16 September 2010, Sozopol, Bulgaria, 2010, pag.491-497.

2. Cristescu, C., Drumea, P., Mathematical modeling and numerical simulation of the tribological behavior of mobile translation sealing subjected at high pressures, In: Hidraulica, Sept. 2008, no. 2, pp. 26-33 (2008).

3. Drumea P., Cristescu C., Fatu A., Hajjam M., Experimental research for measuring friction forces from rod sealing at the hydraulic cylinders, Proceedings-Abstracts of The 11th International Conference on Tribology “ROTRIB’10”, November 4-6 2010, Iasi, Romania, pp. 1.1.7 - 1.1.8

4. M. Crudu, A. Fatu, M. Hajjam, C. Cristescu: "Numerical and experimental study of reciprocating rod seals including surface roughness effects /Etude numerique et experimental des effects de la rugosite sur le compotament des joints hydrauliques en translation. 11th EDF Pprime Workshop: „Behaviour of Dynamic Seals in Unexpected Operating Conditions”, Futuroscope, Septembrie, 2012, Poitiers, France.

5. DRUMEA, P., CRISTESCU, C., OLIVER HEIPL. Experimental Researches for Determining the Friction Forces in the Piston Seals of the Hydraulic Cylinders /Experimentelle Untersuchungen zur Bestimmung der Reibkräfte in Kolbendichtungen von Hydraulikzylindern. In: PROCEEDINGS of The 17-th International Sealing Conference ISC-2012, 13-14 Sept. 2012, STUTTGART, Germany.

6. Calinoiu C., Senzori si traductoare (Sensors and transducers), vol. I, Technical Publishing House, Bucharest, (2009).

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STAINLESS STEEL COLD-WORK HARDENING THROUGH

CAVITATION

Ilare BORDEAȘU1, Ion MITELEA2 Mircea Octavian POPOVICIU3, Marcela SAVA4

1 „Polytechnic“ University of Timisoara, Mihai Viteazul No.1, 300222, Timisoara, Romania, e-mail: ilarica59@gmail.com 2„Polytechnic“ University of Timisoara, Mihai Viteazul No.1, 300222, Timisoara, Romania, e-mail: ionel_mitelea@yahoo.com 3Academy of Romanian Scientists, Timisoara Branch, Mihai Viteazul No.1, 300222 Timisoara, e-mail: mpopoviciu@gmail.com 4„Polytechnic“ University of Timisoara, Mihai Viteazul No.1, 300222, Timisoara, Romania, e-mail: marcela_sava@yahoo.com

Abstract: Manufacturing hydraulic machinery runners with improved cavitation erosion resistance and in the same time with good welding ability is a great challenge for the specialists in design and maintenance of such devices. A good choice is the use of steels with austenitic structures having in the chemical composition 10% of nickel and 2% to 24% of chromium. Upon these types of steels, in the Cavitation Laboratory of the Timisoara Polytechnic University were undertaken extensive researches. It resulted that the best behavior was obtained with the steels having in the structure both austenite and martensite. For such steels the hardness of the attacked areas receives increased hardness as a result of the implosion of cavitation bubbles.

Key words: stainless steels, cavitation erosion resistance, microstructure, microhardness

1. Introduction Cavitation erosion and the subsequent repair works remain important problems in running hydraulic power equipments, especially great turbines and pumps [1], [2], [7]. The use of austenitic stainless steel is a favorable solution because its weld ability is very good. When the austenite is unstable its hardness is increased during the implosions of cavitation bubbles [6]. In conformity with Schäffler diagram, such structures can be obtained by maintaining in the chemical composition a constant nickel level and modifying gradually the chromium content. In this way it can be obtained combined structures of austenite plus martensite or ferrite. The austenite plays an important role because it gives good welding abilities and simultaneously offers an improved erosion resistance.

2. Researched materials The researched steels are employed for manufacturing hydraulic machinery blades or even entire runners as well as for repair works of cavitation eroded zones. The samples from which the specimens were realized were obtained through casting [4], [5]. Before specimen manufacturing, the samples were subjected to specific heat treatments, namely homogenizing annealing followed by a high temperature tempering and a solution quenching with cooling in water or air, depending of the structural constitution [5]. The eight researched steels have reduced carbon content, in order to favor the welding repair works. For obtaining the wanted final chemical composition [5], the prescriptions offered by the Expertise Center for Special Materials (CEMS) of the Bucharest Polytechnic University were used. Because the present work analyzes the effect of cavitation and material structural constitution upon micro hardness, in Table 1 is given the structure constitution established with the Schäffler Diagrame (Fig. 1) for equivalent content of chromium (Cre) and nickel (Nie) [4].

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Fig.1. Schäffler Diagram and the positions of the researched steels [2]

Table 1 Microstructural constitution [4]

Steel Symbol

(Ni-Cr) Cre [%]

Nie [%] Carbon Content

[%] 10-6 11,924 15,173 32%M+68%A

≅1.0 10-10 14,919 14,854 100%A 10-18 22,414 14,138 98%A+2%F 10-24 30,362 15,101 81%A+19%F 10-13 13,209 11,454 55%M+45%A

≅0.036 10-14 15,022 11,4935 30%M+70%A 10-16 17,824 11,515 100%A 10-18 19,610 11,508 93%A+7%F

Note: M-martensite, A-austenite, F-ferrite The cavitation erosion resistance of the structural constitution was analyzed in [4]. Because the chemical composition of the steels is not a standard one, in the present work the steels were symbolized in a different way that those used in [4], but it easy understandable while it gives the approximate values of the basic chemical elements nickel and chromium.

3. Method and test device The cavitation erosion tests were effectuated in the T1 cavitation vibratory facility, with nickel tube, in the Cavitation Laboratory of Timisoara Polytechnic University [2]. Even if the device does not respect the ASTM G32-2010 Standard [9], all tests respect the indications of the ASTM Standard. The used liquid was the water from the urban water-supply network at a temperature of 21±10C. From the cavitation erosion lost masses, using the relation (1) was determined the mean depth erosion (MDE) and with (2) the mean depth erosion rate (MDER).

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MDE = )d

M4( 2p

i12

1i ⋅π⋅ρ∆⋅

∑=

[mm] (1)

MDER = i

2p

i

td60M4∆⋅⋅π⋅ρ⋅∆⋅

[mm/hours] (2)

where: ∆Mi - is the mass loss, in the measuring interval “I”, in grams, ρ – is the steel density, in grams/mm3, ∆ti – is the exposure time of the measuring inteval „i” in minutes, i = 1,2, 3...12 – is the measuring interval (for i= 1, ∆t = 5 min., for i = 2, ∆t= 10 min. and for i= 3...12, ∆t= 15 minutes), dp –diameter of the area exposed to cavitation (dp= 14 mm).

The MDER was computed with relation (2) finally were plotted the diagrams MDER (t) (of the type presented in Fig. 1) which allow to determine the parameter 1/MDERs, (where MDERs is the stabilized value), expressing the cavitation erosion rate resistance.

Fig.1 Dependence of mean depth erosion rate against exposure time (qualitative curve)

4. Experimental researches. Discussions It is known that austenite, especially those labile, during the repetitive impact with the shock waves or the micro jets formed during the implosions of cavitation bubble, is hardened [5], [7], [8]. This hardened thin layer gives an increased erosion resistance to further cavitation implosions [5]. The present work put into evidence the cavitation effect upon the variation of the Vickers hardness (HV), at the end of the 165 minutes of intense cavitation attack and correlates this increased hardness with the parameter 1/MDER which represents the resistance to cavitation erosion. The Vickers hardness measured in points situated at 1-2 mm distance, Fig. 2, has ±2.3% measurement error and is presented in Table 2.

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Fig. 2 Vickers micro hardness measurements in the layer adjacent of the surface eroded by cavitation

Table 2 Measured micro hardness

Steel

Hardness HRC

Vickers micro hardness (µHV0,1) Field 1 Field 2 Field 3 Mean

10-6 48,3 245 256 270 257

10-10 45 230 236 239 235

10-18 38 212 219 214 215

10-24 30 213 209 214 212

10-13 26,5 243 259 269 257

10-14 35.2 256 272 258 262

10-16 30,9 241 232 238 237

10-18 38,3 237 221 226 228

In Fig. 3-5 are presented the variation of mean depth erosion (MDE), mean depth erosion rate (MDER) and cavitation erosion resistance (CER) against the micro hardness measured after 165 minutes of exposure at cavitation. The numbers used in this three pictures correspond to various chemical composition as follows: 1 represent 10-6, 2 represent 10-10, 3 represent 10-18, 4 represent 10-24, 5 represent 10-13, 6 represent 10-14, 7 represent 10-6, 8 represent 10-18. Each picture contains seven lines, three with great thickness and symbolized A, B, C representing the variation of MDE, MDER and CER against micro hardness and four with slim lines and symbolized I, II, II and IV which contain the materials with approximate the same structure.

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Fig. 3 Mean depth of erosion against micro hardness.

Fig. 4 Mean depth erosion rate against micro hardness

Fig. 5 Cavitation erosion resistance against micro hardness

The lines A show that regardless of the carbon content, when the hardness increases, the mean depth erosion MDE (Fig. 3) and the mean depth erosion rate MDER (Fig. 4) decreases while the

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cavitation erosion resistance CER (Fig. 5) increases. This is a characteristic tendency for austenitic structures [3], [7], [8]. The lines B (for steels with a content of 0.036% carbon) and C (for steels with a content of 0.1% carbon) show the important influence of the carbon content upon the hardness. For the steels with a greater content of carbon (line C) the hardness of the attacked layer does not present important increases under the successive cavitation bubble implosions, but even so the erosion resistance is very good. It can be seen from Table 2 that the hardening phenomenon is accentuated for the steels having in structure both austenite and martensite (the structure with the greatest hardness being martensite). The laboratory researches show also that there are steels with different hardness (steels 2, 3, 4 marked through the curve III, as well as 5 and 6 marked with the curves IV) with approximate the same cavitation erosion. In the same time there are other steels with the same hardness but with different erosions (steels 2 and 7 marked with curve I as well as the steels 1 and 5 marked with the curve II). These facts can be justified through the different chemical composition and also different structural constituents.

5. Conclusions As a general feature, the layer subjected to cavitation of the stainless steels present a micro hardness increase as the result of the cavitation bubble implosions. The existence of austenite (especially the labile one) in the microstructure of steels improves the cavitation erosion resistance, as a result of the cold-work hardening through the repeated implosions of the cavitation bubbles. The stainless steels with a structure formed by austenite and martensite present a better cavitation erosion resistance in comparison with those having an austenite-ferrite or even a pure austenite structure (the case of the steel with 68% austenite and 32% martensite) as a result of the hardness increase given by the martensite.

References

[1] ANTON I., Cavitatia, Vol I, Editura Academiei RSR, Bucuresti, 1984. [2] BORDEAŞU I., Eroziunea cavitaţională a materialelor, Editura Politehnica, Timişoara, 2006. [3]BORDEASU I., MITELEA, I., KATONA, S.E. Considerations regarding the behavior of some austenitic stainless steels to cavitation erosion, METAL 2012, 21th International Conference on Metallurgy and Materials, May 23-25, 2012, Brno, Czech Republic, pp.730. [4] BORDEASU I., POPOVICIU, M. O., Cavitation erosion resistance for a set of stainless steels having 10 % nickel and variable Chromium concentrations, Revista hidraulica, nr. 2013, pp. [5] KARABENCIOV A.,. Cercetări asupra eroziunii produse prin cavitaţie vibratorie la oţelurile inoxidabile cu conţinut constant în nichel şi variabil de crom, Teza de doctorat, Timișoara, 2013, pp.188 [6] LAMBERT, P., Déformation plastique et résistance à l’érosion de cavitation d’aciers inoxydables austénitiques, Mémoire présenté en vue de l’obtention du grade du maître est sciences aplliqueés, 1986, Montréal, Canada, pp.110-197 [7] MILICENCO S.L., Repararea distrugerilor prin, cavitaţie la turbine hidraulice (traducere din limba rusă), 1971 [8] MITELEA I., - Studiul metalelor, Litografia Institutului Politehnic”Traian Vuia” Timisoara, 1983. [9] *** (2010). Standard method of vibratory cavitation erosion test, ASTM, Standard G32-10

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SIZING SOLAR CIRCUIT CORRESPONDING TO A SOLAR INSTALLATIONS FOR PREPARATION HOT WATER SYSTEMS

Adriana Gruia1

1 University Politehnica Bucharest, Biotechnical Faculty of Engineering, gadriana43@yahoo.com

Abstract: In this paper, I present the appropriate sizes for sizing solar circuit a solar system hot water such as the required flow forced circulation pump for each square meter of solar collector installed, the flow area through the pipes solar circuit, the amount of antifreeze used for filling the solar circuit entire length of the pipes that form the solar circuit, the speed of the water in the solar circuit pipes, hydraulic power pump power absorbed by the electric motor pump. The solar system object of this study is functional throughout the year, in summer for hot water and the cold season to contribute to preheat cold water in the boiler, followed by raising the temperature up to 45oC water use to be carried out by heating the boiler (and the condensing gas), or by a 2kW electric resistance heater mounted For this purpose, choose a bivalent boiler with two coils and electrical resistance of 2 kW. Basic options for choosing solar thermal system for domestic hot water is to optimize the investment and operating costs. For this purpose we adopted the solution of solar thermal energy production throughout the year

Keywords: solar system, solar heat, solar collector field

1. Introduction

Solar energy is the ultimate source that is external to Alternative energy resources currently exploited [1]. The sun is a star with its own light, formed of 95% hydrogen and helium. Sun temperature at the surface is of 6000 K, and its center 15m is K. The energy produced by the Sun in one second is 4 • 1033 ergs. It is produced by thermonuclear reactions, in particular proton-proton type, in which the atomic nuclei of hydrogen are converted to 4 million tons of helium, releasing energy, the second mass. Earth receives only part of the energy of two billion cut from the sun. Derived from direct solar radiation and diffuse radiation snapshots can be used to produce heat or electricity. Some authors have studied their works to determine the angles used in monitoring the sun in the sky [2]. Production of low temperature heat (below 100oC) is based on technology that uses low-temperature solar thermal collectors. Low temperature solar panel is made from a high surface laminar enclosure at the top is covered with a glass film, and on the bottom with a black absorbing layer (black body) which is designed to absorb light that passes through the glass plate [12]. The thermodynamic conversion of solar energy is made up of: a concentrated solar radiation collector, a suction device and storing the collected thermal energy and a heat transfer device, all connected to a turbogenerator group which operates according to an more or less classical [5,7]. The power of such plants can reach up to hundreds of MW fraction [3]. Solar collectors which converts solar energy into thermal energy is classified into two categories: - collectors without concentrating solar radiation, characterized in that the absorber is equal to the surface to intercept sunlight; - collectors to concentrate solar radiation, characterized in that the surface of well has different forms based on reflection and refraction to increase as much radiation flux density. Fields of application are the main types of sensors: - temperature range up to 100oC. Plane collectors are used without concentration in heating and domestic hot water in drying and desalination plants, etc.;

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-the temperature of the order of 300-500oC. Sensors are used with cylindrical-parabolic concentrator in hot water production plant or steam at high pressure; -600-900 ° C temperature range. They are used paraboloid of revolution sensors concentrator in the technological processes for the thermal decomposition of substances, and to produce mechanical work and electrical energy; -Very high temperature range 3000-5000oC. Sensors are used to focus radiation with heliostats and receiver tower in research material. For hot water collectors are used without radiation concentration. Some authors have presented their work in detail in monitoring weather station atmospheric parameters including sensor for measuring solar radiation intensity [6,11]. Operation of the solar collector can be explained simply considering a plan collector, like that shown in figure 1:

Figure 1 Plane collector [7]

Plane collector consists of the following main parts: 1 - absorbent surface which is generally made of a metal plate coated with black paint in order to increase the absorption of solar radiation and a lower emissivity;

2 - piping system through which the heat carrier agent; 3 - the transparent area made of one or more layers of glass plate with a thickness of 3-4

mm; 4 - thermal insulation is to reduce heat losses of the collector, is made of materials having

poor conductivity; 5 - housing that protects the entire set of sensor against mechanical shock. Heat carrier fluid is usually made of water, ethylene glycol or air.

2. Materials and methods

When choosing a solar system for hot water, you firs need to set the preferred temperature hot water usage and quantity and distribution needs throughout the day. Temperature of hot water use in most practical installations in operation temperature is 450C. Hot water needs, depend on the attitudes and habits of consumers and the characteristics and specific features of each application.

The study concerns a family home consists of four that has a fuel consumption of 50 litters / person / day, so the solar system will need to produce 200 litters of hot water daily.

Distribution of daily consumption of hot water, over 24 hours is considered statistically consistent with values determined by measurements.

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Scheme of the solar system and equipment package consisting of components is shown in figure 2:

Figure 2 Schematic structure of the solar system [10]

3. Results and discussion Sizing solar circuit

Required flow circulating pump P1 between 40 and 80 l / h per square meter of solar panel

installed [4]. Choose an average flow of 60 l / h so that the pump that circulates the heat flow through vacuum tube collector panel is:

6--3

1 1061,67 3600

10222l/h 2227,360 ⋅=⋅

==⋅=PD m3/s

DP1 = 61,67·10-6 m3/s. Tube solar collector panel has diameter φ = 22 mm, so the cylinder S1 and connecting pipes between the solar collector and the tank coil.

obtained d = 22·10-3 m. The flow through the pipe section solar circuit:

6622

103804

10224

−−

⋅=⋅⋅

=⋅

=ππ dA m2.

Pipe section is: A = 380 • 10-6 m2. Volume of antifreeze used to fill the entire solar circuit offered to solar system is 20 liters. Obtained heat volume V = 20 • 10-3 m3. Length of pipelines that form the solar circuit is:

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63,52103801020

6

3=

⋅⋅

== −

−

AVl m.

obtained l = 52,63 m. It follows that the length of pipe between the collector and the tank is 52.63 / 2 = 26.31 m Speed of heating by solar circuit pipes:

16,0103801067,61v 6

61 =

⋅⋅

== −

−

ADP m/s.

The same result is obtained, and if we calculate the Reynolds number, given the kinematic viscosity of the water, respectively ν = 2,3·10-6 m2/s [8].

1552103,21022

1067,6144Re 63

61 =

⋅⋅⋅⋅⋅⋅

=⋅⋅

⋅= −−

−

πνπ dDP

For Re <2300 shows that in the solar circuit heat flow is laminar. Speed of heating by solar circuit pipes:

16,01022

103,21552Rev 3

6=

⋅⋅⋅

=⋅

= −

−

dν

m/s

So the speed of the water is v = 0,16 m/s. During the circulation of the 20 liters of freezing resulting from the relationship

5,560

329s 32916,063,52

=====vlt min.

Hydraulic power of the pump is given by HDgP PH ⋅⋅⋅= 1ρ

- ρ = density of heat [kg/m3]; - g = acceleration of gravity (g = 9.81 m/s2); - DP1 = flow circulating pump; - H is the height of head hydraulic or equal to useful work in N•m or mm of water relative

to the weight force of the liquid transported by the pump shall transmit liquid. Această mărime este proporţională cu pătratul vitezei de rotaţie a turbinei şi este independentă de densitatea lichidului transportat. This amount is proportional to the square of the speed of rotation of the turbine and is independent of the density of the liquid transported.

If we consider H = 25 m, the strength of the hydraulic pump is set to 12,15251067,6181,91000 6 =⋅⋅⋅⋅= −

HP W. The power absorbed by the electric motor of the pump is:

79,1785,012,15

===ηH

aPP W.

Solar circuit pump hot water is VORTEX type and has a rated output of 25 W. Conclusions For the chosen solution (vacuum tube collector bivalent and electrical resistance), I sized solar circuit of the hydraulic (geometric dimensioning of pipes, the speed of the water, hydraulic power pump). Especially solar panel presents a major advantage to be taken into account in the sense that outside a maximum efficiency of 80% the advantage that installs with very simple installation procedure. The entire solar system can be installed and functional tests before actually mount the solar vacuum tubes. They can be mounted at the end of trial operations of the solar system in a very short time and very simple installation procedure.

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Sizing collector was chosen so that the water temperature in the storage cylinder to fall during the warm season the average value of over 60°C, which ensures sterilization of the water stored to the Legionella bacteria. Since the boiler provides hot water at a temperature of 60oC for hot water at a temperature of 45oC have provided a mixer located at the outlet of performing mixed water boiler, ensuring a constant flow regardless of changes in temperature and pressure cylinder.

B I B L I O G R A F I E

1. Colectiv de autori - Dicţionarul Enciclopedic al Academiei Române, vol. IV 2. C. O. Rusănescu, L. David, G. Paraschiv, G. Voicu, M. F. David, M. Rusănescu, Solar

Radiation Monitoring, 01.10.2009 Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Series Agriculture, Vol.66, Iss.2, ISSN 1843-5246 (print), ISSN 1843-5386 (electronic), pp.198-203, 2009;

3. Lucian V.E. - Surse alternative de energie, Editura Matrix, 2011 4. Ilina M., Brandabur C. - Energii neconvenţionale utilizate în instalaţii din construcţii,

Editura Tehnică, 1987 5. Bostan I., Dulgheru V., Sobor I. ş.a. - Sisteme de conversie a energiilor regenerabile -

capitolul II - Energia solară, Editura Tehnica-Info, Chişinău, 2007 6. Carmen Otilia Rusănescu, Gigel Paraschiv, Gheorghe Voicu, Marin Rusănescu

Comparative Analysis of Atmospheric Temperature Values, Relative Humidity In 2009 And 2010 In West Side Of Bucharest City, Bulletin USAMV Agriculture, 68(2)/2011, Print ISSN 1843-5246; Electronic ISSN 1843-5386, pag. 130-138

7. www.megasun.com - sisteme solare termice 8. www.arpicus-solar.com; 9. Kicighin M.A., Kostenko G.N. - Schimbătoare de căldură şi instalaţii de vaporizare,

Editura Tehnică, Bucureşti, 1958; 10. www.aqua-eco.ro - Colector solar cu tuburi vidate tip HEAT-PIPE - Manual de punere în

funcţiune, utilizare şi întreţinere. 11. C. O. Rusănescu, I. N. Popescu, M. Rusănescu, L. David - Analysis of variation in

relative humidity in autumn 2009, Revista International Journal of Energy and Environment, Issue 4, Volume 4, 2010, pp. 113-121, ISSN: 1109-9577. http://www.naun.org/journals/energyenvironment/2010.htm, tp://www.naun.org/journals/energyenvironment/19-468.pdf.

12. Tănăsescu F.T. - Conversia energiei - tehnici neconvenţionale, Editura Tehnică, 1986

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THE 3D BLADE SURFACE GENERATION FOR KAPLAN TURBINES USING ANALYTICAL METHODS AND CAD TECHNIQUES

Teodor MILOS1, Mircea Octavian POPOVICIU2, Ilare BORDEASU3,

Rodica BADARAU4, Adrian BEJ5, Dorin BORDEASU6

1 „Polytechnic“ University of Timisoara, Mihai Viteazul No.1, 300222, Timisoara, Romania, E-mail: teodor.milos@gmail.com 2 Academy of Romanian Scientists, Timisoara Branch, Mihai Viteazul No.1, 300222 Timisoara, E-mail: mpopoviciu@gmail.com 3 „Polytechnic“ University of Timisoara, Mihai Viteazul No.1, 300222, Timisoara, Romania, E-mail: ilarica59@gmail.com 4 „Polytechnic“ University of Timisoara, Mihai Viteazul No.1, 300222 Timisoara, E-mail: badarau_r@yahoo.com 5 „Polytechnic“ University of Timisoara, Mihai Viteazul No.1, 300222, Timisoara, Romania, E-mail: adibej@yahoo.com 6 VIA University College, Chr M Østergaards Vej 4, 8700 Horsens, Danemarca, E-mail: dorin_craiova@yahoo.com Abstract: In the recent past, when the CAD techniques were not disposables, the operations in discussion were made through graphical constructions or in graphic-analytical mode, direct on the board or graph paper, using a lot of time and obtaining low precision. When the results were unsatisfactory all was taken again from the beginning. In actual conditions, having at command program mediums and graphical representation with high performance, their employment became a necessity in the graphical construction of the blade surfaces and the adjustment of the airfoils from different calculus sections. In this paper, simultaneously with CAD techniques are presented the results obtained for a hydraulic turbine blade computed through well established methods. As a result of hydrodynamic calculus, the geometrical characteristics of the airfoil cascades in each calculus section were obtained. From hydrodynamic conditions results also the stagger angle of the profiles and the adjustment in blade assembly is made ulterior from geometrical conditions. The development of those phases must use the CAD techniques. Plotting the used airfoils at a reasonable resolution, necessitate for the pressure side at least 100 points and the same figure for the suction side. Because the great number of computing cross sections (minimum 10), the manually plot became counterproductive. The CAD possibilities consist in the use of the TurboPASCAL and AutoLISP programs for 3D plotting in AutoCAD. The data files are introduced in the AutoLISP program which realizes the 3D plotting. The obtained graphical image is analyzed using the facilities of the AutoCAD. If adjustments are needed, the numerical program must be again operated to modify the necessary parameters. Finally the 3D blade image is introduced in the work drawing together with all needed details. Keywords: Kaplan turbine, blade surface, CAD techniques

1. Introduction

The hydrodynamic calculus represents only a small part of the Kaplan turbine design, [1], [2]. An important next step is the graphical construction of the blade and assembling of them into the runner. In the past, when CAD techniques were not available, these operations were made by graphical constructions or graphic-analytically, directly on the drawing board or on the scale paper, which take a lot of time and has reduced precision, [5], [6]. In the case of unsatisfactory result all must be taken from the beginning. In the present, having access to computer programs provided

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also with very performing graphical representation, it is a necessity to use them for graphical definition of the Kaplan turbine runner blade. From hydrodynamic calculus, are obtained the geometrical characteristics of the airfoil cascades in each calculus section, [1], [2]. The ordering and numbering of the calculus sections is from 0 to n, beginning with the hub section (section 0) and finishing with tip section (section n). The chosen number of sections is 11. Those initial dates for the graphical construction of the blade are presented in Table 1.

Table 1. Runner geometric characteristics obtained with a classical method, using NACA airfoils Number of sec-

tion

Profile Type

Radius of calculus section

r [mm]

Length of the profile

l [mm]

Stagger angle βs[°]

Relative thickness

[d/l] 0 NACA 4412 600 694.2 36.0 0.12

1 NACA 4411 665 712.6 29.5 0.11

2 NACA 4410 730 748.3 25.0 0.10

3 NACA 4409 795 793.4 22.0 0.09

4 NACA 4408 860 841.9 19.7 0.08

5 NACA 4407 925 890.5 17.9 0.07

6 NACA 4407 990 939.8 16.4 0.06

7 NACA 4406 1055 988.4 15.2 0.05

8 NACA 4406 1120 1036.0 14.2 0.04

9 NACA 4406 1185 1083.0 13.3 0.03

10 NACA 4406 1250 1128.0 12.5 0.02

2. Airfoil design in the own system of representation

Initially, the geometry of the airfoils is taken in agreement to the catalogue data or the relations given for the NACA airfoil numerical code (with four, five or six digits), [7]. In dimensionless terms all dimensions are reported to length “l” of the profile chord. The NACA

airfoils are given by the camber line function,

lx

ly f , and the thickness function,

lx

lyd . The

thickness function defines semi-thickness of the profile measured to the normal of the camber line,

Figure 1. Relative abscissa of the maximum thickness is at 3,0max =l

xd

Figure 1. NACA airfoil geometric construction

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It can be seen that the camber function is defined by two parabola arcs perfectly jointed so that airfoil camber line to be continues on the interval [0, 1]. Profile construction and implicit the blade is made through N points computed and distributed on the pressure side and respectively on the suction side. The simplest distribution (digitization) of the points is a uniform one and is realized using equal intervals for x between 0 and 1. This digitization has the disadvantage that in the zones where the curvature of the profile is more pronounced (especially at the leading edge) the smoothness of the curve is not very good. Therefore the correct option is the use of non-uniform distribution for different domains, amplifying the number of points at the leading edge. Working on the interval [0, 1], the best non-uniform distribution is offered by trigonometric functions. If N is the maximum number of intervals and i is the index of a current point, i=0...N, let it be ti the argument of the trigonometric function defined of being, [3]:

),...1,0( 12

NiiN

ti ==π (1)

The abscissa of the digitization xi, is computed with the relation:

)cos(1 ii tx −= (2)

It can be observed immediately that for the extremities, just the extremes values, 0 respectively 1 are obtained and the maximum density area is in the proximity of 0, i.e. at the leading edge of the profile. This option will be reflected in all ulterior calculus and will affect favorably the accuracy and smoothness of the blade surfaces. Forwards, to simplify the relations, the dimensionless expression will be abandoned and the employed values are:

• (xex, yex), the coordinate of the current point for the suction side of the airfoil • (xin, yin), the coordinate of the current point for the pressure side of the airfoil • (xcl, ycl), the coordinate of the current point for the camber line of the airfoil • daf (xcl), thickness function

The abscissa xcl is identical with xi, abscissa of non-uniform distribution. According to Figure 1, and using the calculated values for the camber line function and the thickness function, the points for the pressure side and the suction side can be obtained with the relations, [3], [4]:

−=

+=

)cos(

)sin(

clafclin

clafclin

dyy

dxx

α

α (3)

+=

−=

)cos(

)sin(

clafclex

clafclex

dyy

dxx

α

α (4)

The value αsc represents the angle of the tangent at the camber line in the chosen point. It results from the derivative of the camber line function in the respective point. For NACA profile with four digits the derivatives of the two parabola arcs are:

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( )

( ) ( )

−⋅−

=

−⋅=

xxxfy

xxxfy

ff

f

ff

f

221

22

max2max

max'2

max2max

max'1

(5)

3. The transposition of the airfoils to the stagger angle βs, into the developed plane.

Starting from the representation of the figure 1, the profile will be transposed in the specific working position, in the cascade airfoil, of the corresponding section of the runner. This operation is made in the developed plane of the calculus section. The operation is realized in two stages:

• stage I: the translation of the coordinate system origin in the blade spindle axis, • stage II: the rotation around the blade spindle axis until the stagger angle βs is reached.

The two stages are illustrated in Figure 2 respectively Figure 3.

Figure 2. Stage I, translation of the axis system origin till the blade the spindle axis

The relations used for this translation are:

−=

−=

spd

spd

yyy

xxx

'

' (6)

Figure 3. Stage II: the rotation around the blade spindle axis until the stagger angle, βs is reached

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The relations for the rotation around the blade spindle axis are:

−−=+−=

)cos(')sin(')sin(')cos('

ss

ss

yxYyxX

ββββ

(7)

4. The transposition of the airfoils from plane on the computing cylindrical surfaces

This stage is used for the 3D representation of one or all runner blades. This representation is helpful, in design phase, to see how the airfoils are assembled and correlated in the blade. Working with the cylindrical surfaces, the most adequate coordinate system is a cylindrical one. The initial data for this transposition are the coordinates (X, Y) of the transposed profile at the stagger angle βs in the developed plane. Let the current coordinates of the cylindrical coordinate system to be (r, θ, z). The coordinate r is the radius of the calculus section, Rsec. The θ angle, in radians, results from the condition:

sec

sec RXXR =⇒=⋅ θθ (8)

The plane coordinate Y became z.

Yz = (9)

This mode of representation facilitates the rapid definition of all blades roundabout the rotor hub, because every homologue point for a certain radius differ only with an angle θi, j for every blade. Having the number of blades zb, the angular step θb it is immediately obtained:

b

b zπθ 2

= (10)

The current angle θi, j can be computed with the relation:

bjiji j θθθ ⋅+= ,, where j=0,1,...(zb-1) (11)

In AutoCAD, [8], [10], the representation of the 3D mesh request Cartesian coordinates (x, y, z) which resulted from the cylindrical coordinates according to the relations:

=⋅=⋅=

zzryrx

θθ

sincos

(12)

In figures 4, 5 and 6 it is represented the 3D images of the runner. This representation has a great importance in the design phase because it gives the visualization of every surface detail of the blade regardless of the chosen angle, [4].

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Figure 4. 3D image (hide type) of the runner (blades built with NACA airfoils)

Figure 5. 3D image (render type) of the runner

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Figure 6. 3D image, frontal view of the runner

5. Sequences from the AutoLISP program

;AutoLISP program for 3D, [8], representation of the blades for a Kaplan turbine runner, using NACA profiles (defun c:ROT() (setq Cod (getstring "\n the data file code must be introduced: ")) (setq Z_1 (getint "\n the number of blades must be introduced: ")) (setq Z_2 Z_1) (setq FISIN (strcat "D:\\KAPLAN_3D\\DATE\\INSP_" Cod ".DAT")) (setq FISEX (strcat "D:\\KAPLAN_3D\\DATE\\EXSP_" Cod ".DAT")) …………………………………………………………………………………… (setq fis (open FISIN "r")) (setq poz0 (read-line fis)) (setq Imax (atoi (substr poz0 1 3)) Jmax (atoi (substr poz0 5 3))) (setq poz1 (read-line fis)) (setq Xsup (atof (substr poz1 1 6)) Ysup (atof (substr poz1 8 6))) (setq poz2 (read-line fis)) (setq Xinf (atof (substr poz2 1 6)) Yinf (atof (substr poz2 8 6))) (setq poz3 (read-line fis)) (setq Deltx (atof (substr poz3 1 6)) Delty (atof (substr poz3 8 6))) (setq poz4 (read-line fis)) (setq Scx (atof (substr poz4 1 6)) Scy (atof (substr poz4 8 6))) (CLOSE fis) (command "limits" (list Xinf Yinf) (list Lx Ly)) (command "zoom" "all") ………………………………………………………………………………………… ;------------- Plot the pressure side of the runner blades ----------------------------------- (setq Imesh (1+ Imax)) (setq Jmesh (1+ Jmax)) (setq Fi0 (/ (* 2 pi) Z_2)) (setq dFi 0.0) (setq k1 1) (While (<= k1 Z_1) (command "3DMESH" Jmesh Imesh) (setq fis (open FISIN "r")) (setq poz1 (read-line fis)) (setq poz2 (read-line fis)) (setq poz3 (read-line fis)) (setq poz4 (read-line fis)) (setq poz5 (read-line fis)) (setq j 0) (While (<= j Jmax) (setq i 0) (while (<= i Imax) (setq poz7 (read-line fis)) (setq Fi (atof (substr poz7 1 23)) Ri (atof (substr poz7 25 23)) Zi (atof (substr poz7 49 23)))

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(setq x (COS (+ (* k1 Fi0) Fi dFi))) (setq y (SIN (+ (* k1 Fi0) Fi dFi))) (setq x1 (* Ri x)) (setq y1 (* Ri y)) (setq x2 (* x1 Scx)) (setq y2 (* y1 Scy)) (setq z2 (* Zi Scy)) (command (list x2 y2 z2)) (setq i (1+ i))) (setq j (1+ j))) (CLOSE fis) (setq k1 (+ k1 1))) ;-------------Plot the surface of the hub ---------------------------------------- (setq Fi0 (/ pi 60)) (setq Imesh (/ (+ Imax 2) 2)) (command "3DMESH" Imesh 121) (setq fis (open FISEX "r")) (setq poz1 (read-line fis)) (setq poz2 (read-line fis)) (setq poz3 (read-line fis)) (setq poz4 (read-line fis)) (setq poz5 (read-line fis)) (setq i 0) (while (<= i (+ Imax 2)) (setq poz7 (read-line fis)) (IF (> i 0) (setq poz7 (read-line fis))) (setq Fi (atof (substr poz7 1 23)) Ri (atof (substr poz7 25 23)) Zi (atof (substr poz7 49 23))) (setq j 0) (While (<= j 120) (setq x (COS (* j Fi0))) (setq y (SIN (* j Fi0))) (setq x1 (* Ri x)) (setq y1 (* Ri y)) (setq x2 (* x1 Scx)) (setq y2 (* y1 Scy)) (setq z2 (* Zi Scy)) (command (list x2 y2 z2)) (setq j (1+ j))) (setq i (1+ i))) (CLOSE fis) ;------------- Plot the suction side of the runner blades----------------------------- (setq fis (open FISEX "r")) (setq poz0 (read-line fis)) (setq Imax (atoi (substr poz0 1 3)) Jmax (atoi (substr poz0 5 3))) (setq poz1 (read-line fis)) (setq Xsup (atof (substr poz1 1 6)) Ysup (atof (substr poz1 8 6))) (setq poz2 (read-line fis)) (setq Xinf (atof (substr poz2 1 6)) Yinf (atof (substr poz2 8 6))) (setq poz3 (read-line fis)) (setq Deltx (atof (substr poz3 1 6)) Delty (atof (substr poz3 8 6))) (setq poz4 (read-line fis)) (setq Scx (atof (substr poz4 1 6)) Scy (atof (substr poz4 8 6))) (CLOSE fis) (setq Imesh (1+ Imax))

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(setq Jmesh (1+ Jmax)) (setq Fi0 (/ (* 2 pi) Z_2)) (setq dFi 0.0) (setq k1 1) (While (<= k1 Z_1) (command "3DMESH" Jmesh Imesh) (setq fis (open FISEX "r")) (setq poz1 (read-line fis)) (setq poz2 (read-line fis)) (setq poz3 (read-line fis)) (setq poz4 (read-line fis)) (setq poz5 (read-line fis)) (setq j 0) (While (<= j Jmax) (setq i 0) (while (<= i Imax) (setq poz7 (read-line fis)) (setq Fi (atof (substr poz7 1 23)) Ri (atof (substr poz7 25 23)) Zi (atof (substr poz7 49 23))) (setq x (COS (+ (* k1 Fi0) Fi dFi))) (setq y (SIN (+ (* k1 Fi0) Fi dFi))) (setq x1 (* Ri x)) (setq y1 (* Ri y)) (setq x2 (* x1 Scx)) (setq y2 (* y1 Scy)) (setq z2 (* Zi Scy)) (command (list x2 y2 z2)) (setq i (1+ i))) (setq j (1+ j))) (CLOSE fis) (setq k1 (+ k1 1))) (command "VPOINT" "1,1,0.8" "") ) It can be seen that the starting data are those included in Table 1. The subsequent processing contains a very great volume of calculus. All the six stages of this computation were programmed in TurboPascal language, [9], with a source code having more than 1300 lines. The obtained data were transferred in files, graphical processed in AutoCAD by means of AutoLISP program.

6. Conclusions The presented procedure is completely computerized, without appealing to the classical method, without using graph paper or board graphical constructions. The advantages of the method are:

• the increase of precision, • the increase of the working speed, • immediately verifications of blade geometrical shape and indications if some small

corrections of airfoils length and thickness are necessary, • realizing the files with the 3D geometry of the whole runner which can be used for ulterior

modeling of flow in FLUENT, TASK FLOW or other specialized programs, • a great part of graphical representations and tables can be used directly in the execution

project or even in the manufacture of the blade, • the data being in electronic format are transposable immediately to another scale and used

to realize the model runner.

Acknowledgement This work has been supported by Research Department of “Politehnica” University of Timişoara, Romania.

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REFERENCES

[1] I. Anton, “ Hydraulic Turbines”, Editura Facla, Timişoara, Romania,1979 [2] M. Bărglăzan, “Hydraulic Turbines and Hydrodynamic Transmitions” Editura “Politehnica” Publishing

House, Timişoara, Romania, 2001 [3] T. Miloş, “Optimal Blade Design of Centrifugal Pump Impeller Using CAD Procedures and Conformal

Mapping Method”, International Review of Mechanical Engineering (IREME), Vol. 3, No. 6, PRAISE WORTHY PRIZE S.r.l, Publishing House, ISSN 1970-8734, 2009, pp. 733-738

[4] T. Miloş, “Method to Smooth the 3d Surface of the Blades of Francis Turbine Runner”, International Review of Mechanical Engineering (IREME), Vol. 1, No. 6, PRAISE WORTHY PRIZE S.r.l, Publishing House, 2007, pp. 603-607

[5] L. Raabe, “Hydraulische Maschinen und Anlagen”, Publishing VDI Verlag, Düsseldorf, Teil I + II + III + IV, 1970

[6] Radha Krishna, “Hydraulic Design of Hydraulic Machinery”, Publishing Avebury, Ashghate Publishing Limited, ISBN: 0-29139-851-0, UK, 1997

[7] Zidaru Gh., Mişcări potenţiale şi hidrodinamica reţelelor de profile, Editura didactică şi pedagogică, Bucureşti, 1981.

[8] Stăncescu C., AutoLISP, Manual de programare, Editura. FAST 2000, Bucureşti, 1996 [9] Kovacs S., Turbo Pascal 6.0, Ghid de utilizare, Editura Microinformatica, Cluj-Napoca, 1993 [10] ***, AutoCAD 2010, Autodesk, User’s Guide.

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COMPUTATION OF THE COMPLIANCE MATRIX FOR ROTARY LIP SEAL

Elgadari Ma, Fatu Ab, Hajjam Mb, Belhaq Mc

aUniversité Moulay Ismail, ENSAM, Meknès, Morocco. bInstitutPprime, Département Génie Mécanique et Systèmes Complexes, Futuroscope Chasseneuil, France. cUniversité de Casablanca, Faculty of Sciences, Casablanca, Morocco.

Abstract The understanding and the modelling of the ElastoHydroDynamic(EHD)behaviour of lip seals needed

more than fifty years of continuous investigations. Even if many studies have been dedicated to the

EHD modelling of rotary lip seal,an important aspect has not been well described:any scientific section

of the international literature insists on the calculation method of the seal elasticity.

Thus, the scope of this work is to prospects two different methodsused to calculate the influence

coefficient matrix: by using Boussinesq approach and by using a specific finite element application

developed in Pprime Institute of Poitiers. The resultsshowthat the two approaches leadto important

differences concerning the predictionofseal power lost and leakage.

Introduction

The rotary lip seal is the most common type of rotary shaft seals. It’s used to withstand differences

in pressure, contain lubricant and exclude contaminants such aswater and dust particles. During

the last decades, great efforts have been done to understand and model the lip seal behaviour in

application involving rotary mechanisms.

In most studies found in literature,an important aspect of the models used to predict the behaviour

of lip seal has not been well described: the calculation method of the “influence coefficient matrix”.

Therefore, the aim of this work is to compare twonumerical calculation methods of the “influence

coefficient matrix”. Namely, the Boussinesq method anda Finite Elements (FE) application

developed in PprimeInstitute [1]. To perform this study, the following steps are proposed:

• Defining mechanical behaviour of the lip based on elastomer characterization; Hyperelastic (nonlinear) or Elastic (linear behaviour) ,

• Describing the structural analysis of lip and the different way to compute matrix compliance, • Comparingthe numerical predictions in terms of leakage and power loss, obtained by using

the two compliance matrix.

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Model

Assumptions

Fig.1 shows a schematic diagram of a typical lip seal and the region near the sealing zone. It is

assumed that:

• The seal operates in steady state conditions, • The viscosity of the lubricant is constant, • The air side of the seal is flooded with lubricant, so the reverse pumping rate can always be

calculated, • The average film thickness is uniform in the axial direction.

a) b)

Figure 1: a) Schematic section of radial lip sealb) Schematic diagram of the sealing zone

Governing Equations

In Fig. 1b)x is the circumferential direction and y is the axial direction. The upper stationary surface

represents the lip surface, while the lower moving surface represents the shaft surface.

The Reynolds equation in a Cartesian co-ordinate system takes the form:

𝜕𝜕𝜕𝜕𝜕𝜕

ℎ3 𝜕𝜕𝜕𝜕𝜕𝜕𝜕𝜕 +

𝜕𝜕𝜕𝜕𝜕𝜕

ℎ3 𝜕𝜕𝜕𝜕𝜕𝜕𝜕𝜕 = 6𝜇𝜇𝜇𝜇

𝜕𝜕ℎ𝜕𝜕𝜕𝜕

+ 12𝜇𝜇𝜕𝜕ℎ𝜕𝜕𝜕𝜕

(1)

As the shaft or Lip is considered smooth, we assume:

𝜕𝜕ℎ𝜕𝜕𝜕𝜕

= 0 (2)

In order to take into account cavitation effect, another formulation of equation (1) is developed to

deal with the film rupture/replenishment conditions [2]:

𝜕𝜕𝜕𝜕𝜕𝜕

ℎ3 𝜕𝜕𝜕𝜕𝜕𝜕𝜕𝜕 +

𝜕𝜕𝜕𝜕𝜕𝜕

ℎ3 𝜕𝜕𝜕𝜕𝜕𝜕𝜕𝜕 = 6𝜇𝜇𝜇𝜇.

𝜕𝜕ℎ𝜕𝜕𝜕𝜕

+ + 6𝜇𝜇(1 − 𝐹𝐹) 𝜇𝜇.𝜕𝜕𝜕𝜕𝜕𝜕𝜕𝜕 (3)

Where:

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𝜕𝜕 = 𝜕𝜕𝑝𝑝𝑝𝑝𝑝𝑝𝐹𝐹 = 1,𝑤𝑤ℎ𝑒𝑒𝑝𝑝𝜕𝜕 > 0

𝜕𝜕 = 𝑟𝑟 − ℎ , 𝑟𝑟 =ρρ0ℎ𝑝𝑝𝑝𝑝𝑝𝑝𝐹𝐹 = 0,𝑤𝑤ℎ𝑒𝑒𝑝𝑝𝜕𝜕 ≤ 0

(4)

ρ and ρ0 are densities of lubricant-gas mixture and lubricant respectively.

The boundary conditions are:

• p(x,0)=pf (sealed fluid pressure) • p(x,b)=p0 (Air pressure) • p(0,y)=p(λ,y) (Axisymmetric condition)

Film Thickness

h = h2 + hd + h0 (5)

Where :

• h2(x,y):Lip surfacefluctuations (Figure 3), • h0: Average film thickness, • hd : Lip deformation, such ashd = [C1]. p − ps,where [C1] compliance matrix and ps the

contact static pressure,

Figure 2 : Deterministic Lip seal and Shaft surface: sinusoidal form

The deterministic form of the lip is given by the following expressions:

• Lip Roughness (Figure 2):

h2(x, y) =H2

2cos

2𝜋𝜋.𝑁𝑁𝑁𝑁𝑁𝑁2𝜆𝜆

(𝜕𝜕 − δ) . 1 − cos(2𝜋𝜋.𝑁𝑁𝑁𝑁𝑁𝑁2

𝑏𝑏𝜕𝜕) (6)

Where H2 is the amplitude of the lip surface, NBX2 and NBY2 arethe number of peaks according

respectively to circumferential direction x and to axial direction y, δ = [C2]. τ is the tangential lip

deformation due to tangential shear stress.

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Structural mechanic analysis

Knowing that a numerical analysis starts with the evaluation of the static dry pressure profile and

contact length, figure 3 shows the FE model of the seal. The model is meshed with axisymmetric

stress elements. The computations are made in large displacement and deformation hypotheses.

The shaft is usually made in more rigid material (typically steel) than the elastomeric seal.

Consequently, it is reasonable to consider the shaft as an analytical defined rigid element.

This result is the starting point of the EHD modelling: the integration of the contact pressure gives

the force that must be balanced by the hydrodynamic pressure. The axial contact length defines

the study domain length in the axial direction. The second length is chosen equal to the roughness

periodicity in the circumferential direction.

Figure.3: FE model of the seal

Hyperelastic / Elastic equivalence

Rare are the studies that have treated of the equivalence between the elastic and hyperelastic

model for a rotary lip seal.In the following, the young modulus E and the Poisson ratio νare

approximated from the Mooney-Rivlin parameters, such as:

𝐸𝐸 = 4(1 + 𝜈𝜈)(𝐶𝐶10 + 𝐶𝐶01)

𝐾𝐾 =2𝜕𝜕

=𝐸𝐸

3(1 − 2𝜈𝜈) (7)

Fig 4 shows the differences in terms of contact width and maximum contact pressure, between

simulations performed by considering a hyperelastic behavior and the equivalent Hookean model.

The differences are estimated for different interferences ranging from4µmup to 450 µm. The

hyperelastic model parameters are: C10 = -2.746MPa, C01 = 4.597MPa and D = 0.001MPa-1.The

equivalent Young modulus is E = 11.1 MPa with ν = 0.499. It can be observed that the increase of

Before assembling After assembling

00.10.20.30.40.50.60.70.80.9

1

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04

Axial position [mm]

Con

tact

pre

ssur

e [M

Pa]

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the interference leads to the increase of the differences between the two cases. This proves that a

precise evaluation of the elastomer behaviour is necessary, especially when the lip/shaft

interference is important.

Figure 4 :Curve equivalence between Elastic and Hyperelastic model

Compliance matrix: FE method

Before computing the compliance matrix, the following hypothesis is made: the radial strain

imposed by the fluid film in contact is small in comparison with the radial strain imposed by the

seal/shaft interference. Therefore, the elastic response of the seal is computed as a linear

perturbation of the mounted seal: the seal material is a classical Hookean model and the

computations are made in small displacement and deformation hypotheses.

Moreover, the lip is considered to have, along a height d,a 3D behaviour. The elastic deformation

of the lip is treated by FE method using elements with twenty nodes for the 3D part and eight

nodes 2D elements for the rest of the seal structure (see Figure 5). In order to take into account

the global axisymmetric hypothesis, rigid beams connect the two faces of the 3D domain, giving

the same displacement for the connected nodes. Two compliance matrixes [C1] and [C2] are

calculated. [C1] is used to compute the radial displacement and [C2] is used to compute the

circumferentially tangential displacement.

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Figure 5: Lip seal 3D finite element model

Compliance matrix:Analytical Method

This is a simplest method based on the Boussinesq-Love approach[3]. The method supposes that

the lip seal elastic behaviour can be approachedby an elastic half-space domain. Therefore, the

deformation field can be estimated by (see figure.6):

d(x, y) =1 − υ2

E

pxj, yjdxj. dyj

(x − xj)2 + (y − yj)2 (8)

Figure 6: Boussinesq model

The relationship between, the fields of displacement [d], and pressure [p], is given by:

[𝑝𝑝] = [𝐶𝐶]. [𝜕𝜕] (9)

[𝐶𝐶] =

⎣⎢⎢⎢⎡ C11 … C1j … C1NN

⋮Ci1⋮

………

⋮Cij⋮

………

⋮CiNN⋮

CNN i … CNN j … CNN NN ⎦⎥⎥⎥⎤

(10)

With𝐶𝐶𝑖𝑖,𝑗𝑗 = 1−υ2

πE

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⎩⎨

⎧yi − yj − d. ln

⎝

⎛xi − xj − c +(yi − yj − d)2 + (xi − xj − c)2

xi − xj + c +(yi − yj − d)2 + (xi − xj + c)2⎠

⎞

+ yi − yj + d. ln

⎝

⎛xi − xj + c + (yi − yj + d)2 + (xi − xj + c)2

xi − xj − c + (yi − yj + d)2 + (xi − xj − c)2⎠

⎞

+xi − xj + c. ln

⎝

⎛yi − yj + d + (yi − yj + d)2 + (xi − xj + c)2

yi − yj − d + (yi − yj − d)2 + (xi − xj + c)2⎠

⎞

+ xi − xj − c. ln

⎝

⎛yi − yj − d + (yi − yj − d)2 + (xi − xj − c)2

yi − yj + d + (yi − yj + d)2 + (xi − xj − c)2⎠

⎞

⎭⎬

⎫ (11)

whered=b/2M , c=λ/2N,N is thenode number according to x direction, M is thenode number

according toy direction and NN isthe total number of nodes.Due to the global axisymmetric, the

deformations are computed in the middle nodes domain and deduced by translation to the rest of

the domain (figure 7).

.

Figure 7: Boussinesq model corrected by extrusion displacement axisymmetric faces

Validation

As indicated in a previous paragraph, in order to compute the compliance matrix, it is assumed that

the elastic response of the seal is computed as a linear perturbation of the mounted seal. So, to

validate this hypothesis, the radial deformation under a uniform unitary pressure field is computed

for both used methods and then compared with a FE results obtained without any simplification

(non-linear model). As the model is axisymmetric, the obtained deformation is constant through the

circumferential direction and only the axial variation is represented in figure8. It can be observed

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that the linear FE model and the non-linear FE model give almost the same elastic response.

However, the Boussinesq-Love method leads to very different results.

Figure 8: Radial deformation of the lip seal surface under a constant pressure (1 MPa)

The comparison between the two presented approaches used to compute the compliance matrix is

extended to the EHD computation of the seal. Figure 9 shows the ratio between the seal

functioning parameters computed analytically by the Boussinesq method and numerically by FE. It

can be noted that, even if easier to implement, the analytical method leads to a under estimation of

the leakage (up to 50% in the presented case) and to an over estimation of the power loss (up to

20%).

Figure 9 : Influence of the compliance matrix computation method over the seal functioning

parameters

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Conclusion

The structural analysis is required to initiate the EHDmodellingof a lip seal. We have shown in this

study that the equivalence between the linear and the hyperelastic model can be verified only for

small displacement (when the interference between the shaft and the seal is small).

After determination of the contact width, we explained two different methods of calculating the

compliance matrix. Then, we have shown that the analytical approach gives deformations10 times

smaller than calculated by Abaqus, without any simplification. In the same time, the numerical

method based on FE computation leads to accurate results. It is next proved that these large

differences in stiffness between the two models lead to important differences in terms of leakage

and power loss predictions, which proves that only the numerical method must be used in EHD

modelling of rotary lip seals.

Acknowledgments

The authors' are grateful to the Technical Centre for the Mechanical Industry (CETIM) – Nantes

that financially supported this work.

References

[1]. R.F.Salant, “Modelling rotary lip seals”, Wear 207, (1997) 92-99. [2]. M.Hajjam,D.Bonneau,”A transient Finite element cavitation algorithme with application to radial lip

seals”, Tribology international (2007),1258-1269. [3]. S.K.Tonder, R.F.Salant,”Non-leaking lip seals: A roughness effect”, Journal of tribology (1992),114-

595.

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MONITORING OF PHYSICAL INDICATORS IN WATER SAMPLES

Rusănescu Carmen Otilia1, Rusănescu Marin2, Stoica Dorel1

1 University Polytechnic Bucharest, Biotechnical Faculty of Engineering, otiliarusanescu@yahoo.com 2 Valplast Industrie Bucharest Abstract: In this paper, are monitored following indicators physics of water in Eforie Nord, Herastrau Mogosoaia Moeciu, Bordei: turbidity, pH, oxygen, conductivity, such variation is made and physical indicators of temperature.

To measure this quality indicator of water, we used: turbidimeter portable microprocessor type HI 93 703, oxigenometer portable microprocessor type HI 9146, pH meter type HI 9214. Natural water quality is determined, in general, all mineral and organic substances, dissolved gases, particulate matter and living organisms present.

Conductivity of water is one of the most used indicators to assess the degree of mineralization, water conductivity measurements allow determination of total dissolved salts in water.

The concentration of hydrogen ions in water (pH), is an important factor determining the reactivity of water capacity, its aggressiveness, ability to provide water for development of various media organizations. Turbidity is due to solid particles or in the form of colloidal suspensions. It is therefore very important to monitor physical indicators of water.

Keywords: pH, turbidity, conductivity, oxygen in water

1. Introduction Water quality is defined by three parameters: basic parameters: temperature, pH, conductivity,

dissolved oxygen, parameters indicative of persistent pollution cadmium, mercury, organo - halogenated and mineral oils optional parameters: total organic carbon, biochemical oxygen demand anionic detergents, heavy metals, arsenic, boron, sodium, cyanide, total oil.

To characterize the quality and degree of pollution of water are used as indicators. They can be classified according to their nature and by the nature and the effects they have on water as: classification by nature quality indicators: Indicators organoleptic (taste, smell);

- Physical indicators (pH, electrical conductivity, color, turbidity); - Chemical indicators. - In this paper, we monitored physical indicators in waters: Herastrau, Eforie, Moeciu,

Mogosoaia 2. Materials and methods

To highlight the portable turbidimeter turbidity we used the Hanna firm. Turbidity was designed in accordance with standard ISO 7027 International, so the unit of measurement of turbidity is the FTU (Formazin turbidity unit). FTU is the same as other internationally recognized unit: NTU (nephelometric turbidity units)

Picture conversion between these units is shown in Table 1.

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Table 1 Picture the conversion

JTU FTU/NTU SiO2 mg/l

JTU 1 19 2.5 FTU/NTU 0.053 1 0.13 SiO2 mg/l 0.4 7.5 1

The tool works by passing a beam of infrared light through a cuvette containing the sample:

Figure 1 Switching the light beam through the cuvette [1]

A sensor placed perpendicular to the direction of light, measure the amount of light scattered

by particles in the sample of existing undissolved. The microprocessor converts the readings into FTU values. Water turbidity is characterized by its lack of transparency due to the existence of particles in suspension.

Total suspension means all components insoluble solids present in a quantity of water and can be separated by laboratory methods (filtration, centrifugation, sedimentation). Gravimetric expressed in mg / l or volume in ml / l. The value of total suspension is particularly important for the characterization of natural waters. Depending on the size and specific gravity, particles are separated in the form of deposits (sediment) or floating on the water surface (floating). Gravimetric suspensions are all insoluble solids that can settle, naturally in a limited period of time.

The conductivity of water is one of the indicators used in assessing the degree of mineralization of waters at least the following reasons:

- Measurements of the conductivity (resistivity) allow determination of the total content of water of dissolved salts in the water;

- Have the advantage of differentiation between inorganic and organic salts (weight) based on specific ion mobility;

- Eliminate errors due to transformation of species of carbonate / bicarbonate by evaporation at 105 0 C (according to the methodology of determining the gravity fixed residue, where the losses are bicarbonates 30%). Conductivity type of firm Hanna HI 99300 is a portable measurement EC/TDS/0C/0F with Enhanced The concentration of hydrogen ions HI 9214 is a compact device pH/0C thin, microprocessor designs to be easily transported. PH electrode has a temperature sensor included for quick and accurate temperature measurements and automatic temperature compensation natural water pH is between 6.5 - 8 as a deviation from these values giving an indication of inorganic pollution.

The concentration of hydrogen ions in water, is an important factor that determines the reactivity of water, aggression its ability to be water environments for the development of various organisms, etc..

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Between the pH of the water and its acidity or alkalinity are not identical. Increased alkalinity or

acidity are not accompanied by corresponding changes in pH due to the buffering capacity of natural waters that have particular. The main natural buffer system is the system of water dissolved carbonic acid / carbonate, the pH of the water is between 6.5-8.5.

Indicators of the oxygen Oxygen gas is soluble and is dissolved in water in the form of O2 molecules, the presence of

oxygen in the water conditioning the existence of a large majority of aquatic organisms. All waters which are in contact with atmospheric air containing dissolved oxygen while groundwater containing very little oxygen. The solubility of oxygen in water depends on the pressure, air temperature, water temperature and salinity. Dissolved oxygen, the most important parameter of water quality in rivers and lakes is the content of dissolved oxygen because oxygen is vital to aquatic ecosystems. The content of oxygen in natural waters must be at least 2 mg / l, while the paint, in particular those operating in the fish farms, the dissolved oxygen content should be 8-15 mg / l.

3. Results and discussion In figure 2 -5, we present the results of measurements of five water samples. From Figure 2-5 it is observed that at low temperatures Herăstrău waters, Eforie North Mogoşoaia are acidic. Waters Moeciu board are alkaline. At higher temperatures than water is alkaline Bran. Lower pH leads to immune disorders.

Turbiditatea la 30.5 0C

5.39

10.950.88

7.67

3.33BordeiHerastrauEforie NordMogosoaiaMoeciu

Turbiditatea la 10 0C

5.69

17.79.24

10.240.78

BordeiHerastrauEforie NordMogosoaiaMoeciu

Turbidity 30.5 0C

5.39

10.950.88

7.67

3.33

Bordei Herastrau Eforie Nord Mogosoaia Moeciu

Turbidity 10 0C

5.69

17.79.24

10.240.78

Bordei Herastrau Eforie Nord Mogosoaia Moeciu

Figure 2 Turbidity at 30,50C and 100C

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ph 30.5 0C

Bordei, 5.28

Herastrau, 5.2

Eforie Nord, 6.6Mogosoaia, 5.5

Moeciu, 7.86

Bordei Herastrau Eforie Nord Mogosoaia Moeciu

ph 10 0C

Bordei, 7.88

Herastrau, 5.7

Eforie Nord, 6.78Mogosoaia, 6.8

Moeciu, 8.54

Bordei Herastrau Eforie Nord Mogosoaia Moeciu Figure 3a pH at 30,50C and 100C

water temperature [0C]

1212.5

12

12.5

12.51111.511

13

11

1312

water sample 1 water sample 2 water sample 3 water sample 4water sample 5 water sample 6 water sample 7 water sample 8water sample 9 water sample 10 water sample 11 water sample 12

Figure 3 bThe pH of the samples at different temperatures Herastrau water

In Figure 3 b we monitored water samples at temperatures between Herastrau [11-13 0C]. Note that the 1-4 water samples had pH values below 7 and from 5 to 12 water samples had pH values above. Table 2 Value pH

water sample

1

water sample

2

water sample

3

water sample

4

water sample

5

water sample

6

water sample

7

water sample

8

water sample

9

water sample

10

water sample

11

water sample

12

water temperature [0C] 12 12.5 12 12.5 12.5 11 12 11 13 11 13 12

pH [ph unit] 6.63 6.48 7.25 6.75 7.4 8 7.6 7.2 7.5 7.29 7.4 7.6

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O2 % 30.5 0C

Bordei, 8.9

Herastrau, 7.5Eforie Nord,

8.2

Mogosoaia, 7.2

Moeciu, 9.4

Bordei Herastrau Eforie Nord Mogosoaia Moeciu

O2 % 10 [0C]

Bordei, 65.5

Herastrau, 9.6

Eforie Nord, 9.9

Mogosoaia, 12.8

Moeciu, 147.7

Bordei Herastrau Eforie Nord Mogosoaia Moeciu

Figure 4 Oxygen content 30,50C and 100C Conductivity [ppm] 30.5 0C

Bordei, 278Herastrau, 285

Eforie Nord, 2000

Mogosoaia, 260

Moeciu, 88

Bordei Herastrau Eforie Nord Mogosoaia Moeciu

Conductivity [ppm] 10 0C

Bordei, 320Herastrau, 300

Eforie Nord, 2000

Mogosoaia, 350

Moeciu, 81

Bordei Herastrau Eforie Nord Mogosoaia Moeciu

Figure 5 Conductivity at 30,50C and 100C

Conclusions Following research, we found that at low temperatures (100C) were the only alkaline water board and Bran these waters with a pH of 7.87 and 8.54. Other water had a pH of less than 7 which are acidic. At higher temperatures (240C), only alkaline water was Bran water with a pH of 7.86, the other four water samples were acid value (below 7). We know that to live a long and healthy life, you have to remove acidic wastes in our body. The best and easiest way to get rid of these acidic wastes is to liquefy them and neutralize them with alkaline water. By removing acidic waste particles in the blood, eliminate the risk of disease. Alkaline water has the ability to neutralize acid and liquefy waste to be eliminated from the body, keeping its alkalinity - so healthy and well. And if turbidity best value (lowest value) was recorded at both temperatures Bran and at low temperatures. Reduction of oxygen below the smooth breathing of fish is one of the common causes of death responsible fish. Just like humans, and fish need oxygen to breathe. Most fish are not able to extract this gas and direct vital air, and instead manage to procure it from the water that surrounds them. If water, however, is low in oxygen, the fish die. Water is indispensable for human body. Under natural conditions, the water is never pure, the it is always a certain amount of chemicals dissolved or suspended.

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Through contact with the environment pollute water reaching to contain a number of substances dissolved or suspended water which prints the physical, chemical, biological and bacteriological.

REFERENCES

[1]. Technical Paper turbidimetru [2]. Technical Paper oxygen meter [3]. Technical Paper conductivity [4]. Manescu S., Cucu M., Diaconescu ML - Chemistry Environmental Health, Medical Publishing House, Bucharest; 1994 [5] Water Framework Directive and the Groundwater Directive. 118/2006/EC

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APPLICATIONS OF PROPORTIONAL PNEUMATIC EQUIPMENT

IN INDUSTRY Sava ANGHEL1, Gabriela MATACHE2, Ana–Maria POPESCU, Iulian-Cezar GIRLEANU

1 National Institute for Optoelectronics, INOE 2000-IHP Bucharest, sava.ihp@fluidas.ro 2 National Institute for Optoelectronics, INOE 2000-IHP Bucharest, fluidas@fluidas.ro

Abstract: This article is an overview of the possibilities of application of proportional pneumatic equipment. Here below are presented proportional directional control valves, proportional pressure regulators, pneumatic positioning axes and some of their future applications.

Keywords: pneumatics, proportional, servo technics, cylinders with embedded displacement transducers, proportional pressure regulators, pneumatic proportional directional control valves, axis controllers

Proportional drive systems are widely used in industrial applications. Pneumatic servo technics is used in automation applications in industry, at machine tools, paper processing industry, civil engineering, textile industry, mobile machines, instrumentation, semiconductor industry, in robotics, in the electrical engineering industry, in production of medicines, in agriculture etc. The proportional equipment is found in pneumatic applications such as: feed control at welding devices, control of speed and braking in mobile machines, sandblasting and cutting operations, adjustment of voltage in wires, at presses, in grinding, for adaptive suspension control etc. This paper presents information about pneumatic proportional directional control valves and regulators and also several top applications of proportional pneumatic equipment. The most important proportional appliances are directional control valves and pressure regulators. The proportional pneumatic equipment with air flow control proportionally to an electrical control parameter is called proportional directional control valves, while devices that adjust air pressure proportionally to an electrical signal (in voltage or current) are called proportional regulators. With their help there can be controlled the rates of movement of mobile subassemblies, clamping forces in actuators of pneumatic robots, and also positioning accuracy of pneumatic axes. Proportional equipment allows change in time or in space of loads involved, of travelling speeds and it can respond to positioning diagrams according to the topics requested by the client. Pneumatic proportional directional control valves are flow control devices directing the air flow to an outlet or the other in varying amounts, given by the size of aperture of holes, proportional to the voltage or amperage of current applied to the coil of the control electromagnet. Figure 1 shows such a proportional directional control valve of the company FESTO (4). The slide valve can move in the directional control valve body, taking positions based on control voltage or amperage. At an amperage or voltage equal to half the signal of the slide valve it takes the central position, according to fig. 1, and closes the inlet port for pressure. If the signal drops, the inlet port is opened by movement of the slide valve and the air is routed to the outlet port A, which can be a pneumatic cylinder PC. Through the joint B the air behind the piston of cylinder is discharged to the atmosphere. On increased signal, the slide valve of the directional control valve moves in the other direction and the air is routed to the hole B of the directional control valve, to the PC. The pneumatic cylinder PC manufactured by FESTO (5) is provided from factory with the displacement transducer TR from which signals are taken over and conveyed to the automation system. The assembly directional control valve - pneumatic cylinder with embedded displacement transducer along with the controller form a positioning axis. Such axes have very high performance concerning positioning possibilities. Thus, the company FESTO assigns as positioning accuracy for a cylinder type dnci with built-in transducer and proportional directional control valve type MPYE, working with the controller type SPC 200, a resolution of 0.01 mm and repeatability less than +/- 0.5. To determine the permissible impact mass, Ml, the following formula is used:

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Ml = 2xEper/v2 – MK (5)

where: - Ml is active permissible mass - Eper is permissible impact energy of the cylinder - V is maximum permissible impact velocity - Mk is constructional mass of the moving part of the cylinder

Fig. 1 Directional control valve by FESTO. 1- aluminum body, 2 – aluminum slide valve, 3- electromagnet actuated at amperage 4-20 mA or voltage 0-10 V DC

Fig. 2 Schematic diagram of operation of pneumatic directional control valve type MPYE

from FESTO.

Through 1 there comes the air at the pressure P and goes to consumers A or B, through the holes 2 or 4, depending on the signal from the automation system. In 5 and 3 there are mounted mufflers made of sintered bronze. These devices have the working characteristic at pressure of 0 to 10 bar, working voltage maximum 17...30V DC and flow rates 100, 2000 l/min.

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Under the action of magnetic field, the slide valve item 2 in Fig. 1 is positioned proportionally to the voltage or electric current towards the body of directional control valve item 1, according to Fig. 3.

Fig. 3 Flow rate of proportional directional control valve q (%) depending on the control voltage (left) and amperage (right)

The device is presented in the version with actuation in voltage or the one with actuation in amperage.

For actuation in voltage 0-10 VDC or amperage 4-20 mA at a voltage of 5 VDC (12mA) the slide valve gets in the central position and the flow rate is 0. When the signal drops below 5 V DC or 12 mA the air is routed proportionally to the signal size towards an outlet port, while when the signal rises above this value, the air is routed to the other outlet port. At the extremities - minimum or maximum voltage or amperage – the appliance allows minimum or maximum airflow rates on those outlet ports.

From its construction it can be noticed that the slide valve is kept in equilibrium by forces proportional to the control current. This equilibrium can be easily affected by external forces derived from accelerations or shocks. It is thus necessary to make precautions such as to mount the axis of the directional control valve perpendicularly to the direction of movement of the body in motion. For proper functioning there is used ungreased air and filters of 5 µ.

The company FESTO also delivers the MPZ module that can generate 6 +1 analog voltage signals through which automation can be made in order to obtain levels of preset speeds.

In the field of pneumatic servo technique applications the company FESTO introduces the bionic hand, Fig. 4, demonstrating the level at which one can get in this area. In this application there are solved issues related to drive, positioning and the level of application force.

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Fig. 4 The bionic hand Another application presented by the company FESTO is a smart sorting system that mimics the wavy surface of water. Thus, on a flat surface there are located intelligent pneumatic cylinders that can be actuated individually. The cylinders operate on a membrane on which objects are placed; these objects can be routed in various directions and thus sorted.

Fig. 5 The way the pneumatic cylinder operates on the conveyor membrane

Fig. 6 Pneumatic conveyor for sorting which mimics waving of liquid surfaces

At INOE 2000-IHP there has been developed by a research team under The INNOVATION Programme a proportional pneumatic pressure regulator with membrane, as shown in Fig. 7.

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Fig. 7 Proportional pneumatic pressure regulator with membrane

A section through this regulator is shown in Fig.8. The device adjusts the air pressure in a circuit depending on the size of an electrical signal.

Fig. 8 Section through proportional pneumatic pressure regulator with membrane

Using proportional devices, there has been developed a dental chair and a small table for the equipment, with height adjustment, seatback tilt adjustment and lifting of the table along with the chair. Fig 9.

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Fig. 9 Dental chair and small table operated by proportional equipment

REFERENCES

[1] REGULATOR DE PRESIUNE PNEUMATIC PROPORTIONAL CU MEMBRANA – Patent no. 118097 / 2002; PhD.eng. DRUMEA Petrin, Dipl. eng. MATACHE Gabriela, Dipl. eng. BREAZU Stefan

[2] REGULATOR DE PRESIUNE PIEZOELECTRIC - Patent no. 118036 / 2002; PhD.eng. DRUMEA Petrin, Dipl. eng. MARIN Mihai, Dipl. eng. MATACHE Gabriela, Dipl. eng. COMES Mircea

[3] REGULATOR DE PRESIUNE SERVOPNEUMATIC - Patent no. 118232 / 2003; PhD.eng. DRUMEA Petrin, Dipl. eng. MARIN Mihai, Dipl. eng. MATACHE Gabriela, Dipl. eng. BREAZU Stefan

[4]- MPYE_EN.pdf* [5]- dnci_en.pdf* * FESTO documentation (available on website www.festo.com)

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AMPLITUDES INFLUENCE ON THE PROCESS OF SEPARATION A

GRAIN SELECTOR

STOICA DOREL1 1 , UniversityPOLITEHNICA of Bucharest, Faculty of Biotechnical Engineering,

dorelstc@yahoo.com

Abstract: The researches aimed to determine the influence of structural and functional parameters of the experimental stand bodies active work on quality indicators and operating. The data recorded in the experiments were statistically designed a series of graphs showing the correlation between the outcome and the functional characteristics accompanied by reports of correlation. Functions developed have allowed us to draw a number of conclusions nature of generalization

Keywords: oscillation frequency, amplitude, velocity, acceleration, site blocks 1. Introduction

Mechanical vibrations are the alternative movements of a point, people or systems of bodies around a reference position considered, [1].

The technique as such is in a range of vibration of the simple harmonic vibration, to the more complex, non-stationary random vibration, [2].

In measuring vibration can use three basic parameters: displacement, velocity and acceleration,[3].

The shape and spectral content of the vibration signal is the same regardless of whether it has one or the other of the parameters, but shows, however, a phase difference between them.

Concludes that there is no preferential parameter measurements of vibration. The most common vibration transducers are those which record the vibration acceleration

as a parameter, called accelerometers. However in practice it is recommended displacement measuring vibration when they

contain low frequency acceleration measurement is recommended for high-frequency vibration, [3]. Recording speed vibration frequencies used in the middle of the vibration velocity as a

parameter providing the flattest frequency spectrum. Other authors in various works conducted various statistical analyzes, [5, 6, 7]. Speed can also be a criterion for assessing the destructive effect that can cause vibration

when the speed is directly related to the energy of vibration.

Fig.1. Vibraţie armonică reprezentată prin parametri săi: deplasare, viteză, acceleraţie [3]

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Practice daily, as is the case of agricultural products processing machinery using vibration in their working process shows that the movement of bodies can be considered as a result of a number of overlapping harmonic vibration.

Thus the harmonic vibration analysis can be considered as a material point elongation of the body of work represents the distance from a point to its reference position, the amplitude of vibration is maximum elongation in meters.

Vibration period is determined by the time in which the complete oscillation (in seconds) the frequency of oscillation representing the number of complete oscillations per unit time (measured in Hz ≡ s-1).

Other parameters can be considered vibration pulsation, ω (rad / s) and the initial phase φ in rad. Speed and acceleration point harmonic vibratory motion of the point are given by rel (1) and (2), [4,8].

)2

cos()2

cos()sin( maxπϕωπϕωωϕωω ++=++=+−= tvtAtAv (1)

)cos()cos( max2 πϕωϕωω ++=+−= tatAa (2)

where: - A - amplitude vibration (maximum elongation) (m); - ω - Pulsation (rad / s); - ϕ - initial phase (rad).

For a harmonic vibration vibration shape and angular velocity remain the same regardless of the parameters considered only between travel speed and introduce a lag of π / 2 as can be seen in Figure 1. The vibrations to which the time-varying amplitude of vibration are called amplitude-modulation, while the vibration frequency and / or time-varying angular frequency is called vibration frequency modulated. Vibration measurement using analog electronics that operate with electrical signals obtained from converting vibrations into electrical current or voltage variations using specialized transducers.

2. Material and methods

During an experiment, the parameters of the practice of experimental plants adjust to the desired values (frequency and amplitude of oscillation) drive motor on and data acquisition system running on the computer monitor appear simultaneously two different graphic sets, showing purchase through the program Labview. On the left side of the screen displays the time variation of accelerations recorded for the four accelerometers placed on the surface of the separation cone graphics signals representing vibrations, while on the right side of the screen are displayed one below the other four graphs that represents the change in oscillation frequency acceleration, motion graphics that are spectrograms of oscillation (vibration spectrums).

In order to determine the influence of vibration amplitude oscillations on the grid tapered experimental determinations were performed for both the experimental stand idle and when driving in pregnancy.

With the help of the purchase made and the program developed in LabVIEW were purchased vibration signals to the four accelerometers placed on the surface of the separating grid. Two accelerometers acquires the signal in the direction of the arm, and the other two in a direction perpendicular to the arm about the drive shaft.

Oscillation frequency of the grid values were taken, recorded and then used in the analysis of experimental research results related to the analysis of the separation of the analysis of vibration spectra acquired from experimental research on vibratory movement of the grid, depending on the speed control knob position the drive motor.

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In Figures 2, 3 and 4 are variations amplitude, velocity and acceleration higher building site load frequency f = 4.6 Hz.

Figure 2. Amplitude variations over using accelerometers mounted on the upper block site

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Figure 3. Speed signal variations over using accelerometers mounted on the upper block site

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Fig.4. Acceleration signal variations over using accelerometers mounted on the upper block site

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Conclusions

1. The variation in time of the forces and moments developed by the vibration generators used in the machines for processing of agricultural products depend on the movement of the body to be driven, and the characteristics of the engine to give rise to unbalanced masses (speed, power).

2. Kinematic study of surface separation (body work) is required to estimate the interaction with the workpiece and its movement on the work surface, coupled with the proper conduct of the process of separation or transport.

3. Differential equations resulting from the theoretical study of vibrational phenomena of oscillating blocks are usually quite difficult to solve, requiring the use of numerical methods and several iterations (maybe hundreds), and graphical plotting vibration parameters (acceleration, speed, travel) may not correspond to the actual spectra determined experimentally.

REFERENCES

[1] Voicu Gh., Stoica D., Ungureanu N. - Influence of oscillation frequency of a sieve on the screening process for a conical sieve with oscillatory circular motion, lucrare publicata în Journal of Agricultural Science and Technology, ISSN 1939-1250, USA June. 2011, Volume 5, No.2 (Serial No.27) [2] Elfverson, C., Regnér, S., Comparative precision of grain sieving and pneumatic classification on a single kernel level, Applied Engineering in Agriculture, p.537-541, Vol. 16(5), 2000; [3] Stoica D., - Contribuţii la studiul fenomenelor vibratorii privind utilajele din domeniul prelucrării produselor agricole (teza de doctorat, septembrie 2011)

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[4] Magheţi I., Voiculescu L. – Mechanical elements applied Printech, Bucharest, 2000 [5] C. O. Rusănescu,I. N. Popescu, M. Rusănescu, L. David - Analysis of variation in relative humidity in autumn 2009, Revista International Journal of Energy and Environment,Issue 4, Volume 4, 2010, pp. 113-121, ISSN: 1109-9577. [6] Carmen - Otilia Rusănescu , Gigel Paraschiv - Influence of Aluminum Content on the Structure of High Strength and Non-alloyed Steel Wires Used in Electronic Nanotechnology Components, Industrial Electronics and Applications (ICIEA), 2012 7th IEEE Conference on, Page(s): 787 – 791, Singapore, ISBN: 978-1-4577-2118-2 [7] CO RUSĂNESCU, G. PARASCHIV, G. VOICU, M. RUSĂNESCU Comparative Analysis of Atmospheric Temperature Values, Relative Humidity In 2009 And 2010 In West Side Of Bucharest City, Bulletin UASVM Agriculture, 68(2)/2011, Print ISSN 1843-5246; Electronic ISSN 1843-5386, pag. 130-138. [8] Munteanu M. – Contributions to study the problem using particle size separation shaker, the thesis.

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