fm hm lab manual aug 2011

Back Side

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Vanjari Seethaiah Memorial Engineering College Dept of Mechanical Engineering

8106464676 [email protected] ii

Vanjari Seethaiah Memorial Engineering College Patancheru, Medak

FLUID MECHANICS &

HYDRAULIC MACHINERY

LABORATORY MANUAL -Srikanth Rangdal

(MTech), B.E

Asst. Professor

Dept of Mechanical Engineering

VSMEC

Department of Mechanical Engineering

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8106464676 [email protected] iii

PREFACE

The problems, man encountered in the fields of water supply, irrigation, navigation and water

power resulted in the development of Fluid Mechanics. Some two hundred years ago man kind’s

centuries of experience with the flow of water began to crystallize in scientific form. Experiments in this

field are intended to make the students understand the different methods of flow rates in pipe flow

and open channel flows, conversion of hydraulic energy possessed by the water in running turbines

and how pumps are used to increase the hydraulic energy of the water etc.

The Laboratory for FLUID MECHANICS AND HYDRAULIC MACHINERIES complements the

learning experience of the lecture. Laboratory exercises provide opportunities for direct study of fluid

behavior. All of the laboratory experiments reinforce material presented during lecture. Some of the

experiments will also expose material that is not presented during lecture. A student is responsible for

the union of the laboratory and lecture experience, not their intersection. The laboratory must be used

as a chance to enhance understanding of FLUID STATICS and DYNAMICS. The following Learning

Objectives for the laboratory give guidance in taking an active role in education.

1. Gain familiarity with physical manifestations of FLUID MECHANICS.

The Experiments deal with the basic fluid properties: Viscosity and Pressure.

i. Static Fluid Forces.

ii. Dynamic Fluid Forces.

iii. The relation between pressure and velocity in a flowing fluid.

These experiments give a first hand experience with fluid behavior. As a result of

performing these experiments one should be able to recognize the effects of fluid pressure

and to relate measurements of pressure to velocity in a moving fluid. In addition to learning

about fluid behavior, one should be able to recognize the Physical Equipment in the

laboratory and explain the basic Operating Principles of the Equipment. One should learn how

to operate the equipment properly and safely.

2. Develop and reinforce measurements skills.

The student should know how to read Gauges, Manometers, Flow Meters, Spring

Scales, and Balance Scales. He should be able to time events with a Stopwatch. He should

strive to measure quantities with the maximum precision of the instruments provided in the

laboratory.

3. Developing and reinforcing skills in documenting observations.

The student should develop good habits in the organization and recording of raw data

in a notebook, and take care to document the data such that it can be analyzed at a later

time. He should sketch the physical apparatus used in the experiment. In doing so, he must

pay special attention to the specific mechanical and operational details that enable the

apparatus to achieve the purpose for which it was designed. He should be able to list and

describe the steps used to obtain the desired measurements. He should be able to identify

whether any actions were taken to improve the outcome of the experiment. Likewise, he

should be able to identify any actions that may have contributed to undesirable outcomes.

4. Developing skills at writing laboratory reports.

The student will create reports to document his measurements in the laboratory. He will

use a writing style and format that is common to technical documentation used in Civil and

Mechanical Engineering. The reports should be complete, yet concise. By writing the report, he

should develop a clear understanding of the laboratory exercise, and communicate that

understanding in his written words.

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8106464676 [email protected] iv

CONTENTS

S. No Name of the Experiment Page No

1. Impact of Jets on Vanes 1

2. Determination of Friction factor in Flow Through Pipes 5

3. Determination of Coefficient of contraction 9

4. Calibration of Venturi meter 13

5. Calibration of Orifice Meter 17

6. Performance Test on Single Stage Centrifugal Pump 21

7. Performance Test on Multi Stage Centrifugal Pump 25

8. Performance Test on Reciprocating Pump 29

9. Performance Test on Pelton Wheel 33

10 Performance Test on Kaplan Turbine -

��

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8106464676 [email protected] 2

Experiment No. 1

IMPACT OF JET ON VANES

Aim:

To compare the Actual and Theoretical Forces for Stationary Vanes of different shapes viz.

Curved and Flat Plates.

Apparatus:

1. Sump Tank storing water for constant supply.

2. Measuring Tank with Piezometer to measure water level.

3. Mono block motor with a Control Valve in the Discharge Pipe for controlling flow.

4. Nozzles of suitable diameters (Only 1 available).

5. Leak-proof Nozzle Housing with Transparent Watch Glass.

6. Flat and Curved Vanes mounted on rod connected with a Weight Balance.

7. Stop Watch to measure Time for Rise of Water.

Theory:

When a jet of water is directed to hit the Vane of any particular shape, a force is exerted on it

by the fluid. This force is large in magnitude, acts as long as the jet is making impact with the plate. It is

termed as Impact Force. The magnitude of this force exerted on the Plate/Vane depends on the

Velocity of Jet, Shape of Vane, Fluid Density and Area of Cross Section of the jet. More importantly, it

also depends on whether the Vane is Moving or Stationary.

In our present experiment, we are concerned about the force exerted on the Stationary

Plates/Vanes. The following are the theoretical formulae for different shapes of vane, based on flow

rate.

1) Flat Plate :

Ft = ρ A V2

2) Flat Plate inclined at θ angle from horizontal:

Ft = ρ A V2 cosθ

3) Hemi – Spherical:

Ft = 2 ρ A V2

4) Curved Plate with angle of deflection 180-θ:

Ft = ρ A V2 (1 + cosθ)

Where

‘A’ – Area of jet in m2

‘ρ’ – Density of water = 1000 kg/m3

‘V’ – Velocity of jet in m/sec

‘Ft’ – The theoretical force acting in the direction of jet.

However the actual force as observed by the Weight Balance is lesser than the one

calculated from above equations. For a given setup the ratio of Actual Force to the Theoretical Force

remains constant. This experiment is aimed at finding the same.

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Observation Table:

Type of Vane S No Time for x=___ cm of

water, t (Seconds)

Reading in Weight

balance, W (grams)

a

Flat

1a.1 1a.2 1a.3

b

Curved Plate

1b.1 1b.2 1b.3

Formulae:

t

xAQ

tank=

A = 4

2d×π

For Flat Vane

Ft = ρ A V2

For Curved Vane Ft = ρ A V2 (1 + cosθ)

9.811000

WWFa ×

+= P

Where,

Atank – Area of Measuring Tank (0.3 X 0.3 m2)

x – Height of water considered in meter (from the table above)

d - Nozzle Diameter (8 mm or 0.008 m)

Ft – Theoretical Force

Fa – Actual Force (from the spring balance) ρ – Density of water = 1000 Kg/m3

A – Area of nozzle

V – Velocity of jet

W – Spring balance reading in grams

WP – Mass of the plates (For Flat Vane: 225 and for Curved Vane: 175)

Calculation Table:

S No Q V = Q/A Ft Fa Co-efficient

Fa/Ft

1a.1 1a.2 1a.3 1b.1 1b.2 1b.3

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Procedure:

1. Fix the Suitable Vane and Nozzle in the Nozzle Housing.

2. Make sure the lower end of Suction Pipe is submerged in the Sump Tank.

3. Open the Control Valve fully and start the Pump.

4. Note down the readings in Weight balance.

5. Measure the Time Taken for ‘_____ cm’ height of water collection in Measuring Tank.

6. Repeat the procedure by changing the Control Valve position for different Spring Balance

readings.

7. Repeat the procedure for another Vane or Nozzle.

Precautions:

1. Pump should not be started if the voltage is less than 180 V.

2. Electrical neutral & Earth connections should be checked correctly.

3. Frequent (at least once in three months) greasing / oiling of rotating parts is necessary.

4. The machines should be operated at least some time every week to avoid clogging.

5. Leakages in the Piping and Nozzle Housing should be checked regularly.

Result:

The Actual Value of Force is always lesser than the Theoretically calculated value because:

a. The velocity of water reduces while rising.

b. There is reduction in velocity while water moves on the Vane.

c. All the water from nozzle doesn’t make impact with the Vane.

The average co-efficient of impact was calculated and found out to be

a. For Flat Plate_______.

b. For Curved Vane _______.

Applications:

The Force of Impact calculated in this experiment is useful in determining the work done and

torque exerted by the jet of water on moving vanes in Impact Turbines (Pelton Wheel).

Questions:

1. Out of the plates, which one has the maximum force of impact?

2. Even though the hemispherical vanes have the maximum force of impact, why they are not

used in Pelton wheel?

3. What is the effect of density of fluid on force of impact?

4. What is the relationship between Newton force and kg. force?

5. What is the conversion factor for l.p.m. to m3/s?

6. What is the difference between Mass and Weight?

7. Why is the Actual Force value lesser than the Theoretically calculated value?

8. What is a nozzle?

9. What is Bernoulli’s theorem?

10. What is the Formula for Force if you know the momentums of the fluid before and after

impact?

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Experiment No. 2

DETERMINATION OF FRICTION FACTOR IN FLOW THROUGH PIPES

Aim:

To determine the Coefficient of Friction for different type of Pipes.

The Apparatus




4. Two pipes with Diameters 15 mm (GI pipe) and 20 mm (GI pipe) for friction loss calculation.

5. A Differential Manometer to measure Pressure Head Difference at two ends in the pipes.


Theory:

Any Fluid flowing through a pipe experiences resistance from the walls of the pipe due to

Shear Forces or in simple terms - Viscosity. The amount of loss depends on the Velocity of Flow and

Area of contact between the Pipe and Fluid Particles. It also depends upon the Type of Flow, i.e.

Laminar or Turbulent. This Frictional Resistance causes loss of Pressure in the direction of flow as shown

in the figure below.

The Drop of head can be calculated by using the Darcy-Weisbach Formula:

d.g.2

4.f.L.Vh

2

f =

From the above formula coefficient of friction of friction will be

2

f

.V.4

.2.d.gh

Lf =

Where,

‘hf‘ – Drop of head (got from the manometer difference).

‘f‘ – Coefficient of Friction

‘L‘ – Length of pipe (1 meter)

‘V‘ – Velocity of flow,

‘g‘ – Acceleration due to gravity, 9.8m/s2

‘d‘ – Diameter of the pipe

The Value of Coefficient of Friction is not constant and depends upon roughness of Pipe inside

Surface and Reynold’s number. Any oil content in water also affects its value.

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Observation Table:

Type of Pipe S No Manometric Reading Time for x = ____ cm

of water h1 h2 h = h1 – h2

A (GI)

d=_____

a.1 a.2 a.3

B (GI)

d=_____

b.1 b.2 b.3

Formulae:

t

xAQ tank=

h1-S

Sh

w

Hg

f ×=

A

QV=

2f

.V.4

.2.d.gh

Lf =

Where,

Atank – Area of Measuring Tank (0.3 X 0.3 m2) x – Height of water considered in m(from the table above)

t – Time taken for x cm of water collection.

hf – head loss due to friction in pipe

d – Pipe Diameter

g – acceleration due to gravity (9.81 m/s2)

L – Length of the pipe in meters

V– Velocity of water flow

Result Table:

A S No Q V = Q/A f faverage

For D=20mm

A=_________

a.1 a.2

a.3

For D=15mm

A=_________

b.1 b.2

b.3

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Procedure:

1. Make sure the Water in Sump Tank is free of any Oil Content.

2. Open all the Outlet Valves, Close all the Valves of Manometer and Start the Pump.

3. Close all Valves, except the Outlet Valve of the Pipe to be tested.

4. Remove all the Air Bubbles from Manometer and Connecting Pipes.

5. Adjust the Flow to get Suitable Readings.

6. Note down the Manometric Readings and time ‘t’ for height ‘x cm’ of water collection in

Measuring Tank.

7. Change the Flow Rate and take similar readings.

8. Repeat the procedure for other pipes.

Note: While measuring the heads, slight variation may occur due to voltage changes, valves etc. in

such cases, average readings may by taken.)

Precautions:






Result:

1. Head Loss due to Friction is proportional to Length of Pipe and Square of Velocity.

2. Head Loss is inversely proportional to inside diameter of pipe.

3. Average value of coefficient of friction, ‘f’ for

a. 15 mm GI pipe : _________

b. 20 mm GI pipe: _________

Applications:

The coefficient of Friction lets us easily calculate the losses if the total length of the pipe is

known and hence lets us easily decide the design parameter of a pipeline to be laid.

Questions:

1. What is the meaning of GI?

2. What is Viscocity? Or State and explain Newton’s law of Viscocity.

3. Explain the different types of Major Losses in a Pipe Flow.

4. What is Darcy Weisbach Equation and what is its use?

5. What is the difference between Head and Pressure?

6. What is the use of Manometer?

7. What is the unit of :

a. Discharge

b. Pressure

c. Specific Gravity

d. Specific Weight

e. Density

f. Viscosity

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Experiment No. 3

DETERMINATION OF COEFFICIENT OF CONTRACTION

Aim:

To determine the coefficient of contraction for a sudden enlargement of given pipes.

The Apparatus




4. A pipe with Sudden Contraction from 25 mm to 15mm diameter. It is provided with valve to

allow or stop water flow.

5. A Differential Manometer to measure Pressure Head Difference at two ends in the pipes.


Theory:

There are many Minor Losses taking place in a Pipe Flow viz. Due to Sudden Expansion, Sudden

Contraction, Obstructions, Entrance and Exit etc. A Sudden Contraction in a Pipe results in Head Loss,

which can be calculated by using the following formula:

2

11

−=

C

2

2c

C2.g

Vh

It is possible to measure the Head Loss directly using Manometer. But holes need to be made

wherever it needs to be calculated, which may create Leakage problems. It can be calculated with

the above formula in case we know the Coefficient of Contraction which is constant for a given Fluid.

The formula for Cc becomes

1+

=

2

c

C

V

2.g.h

1C OR

)V2.g.h(

VC

2c

2C

+=

Where,

‘hc‘ – Drop of Head (got from the manometer difference).

‘V2‘ – Velocity of Flow after Contraction,

‘g‘ – Acceleration due to Gravity, 9.8m/s2

‘Cc‘ – Coefficient of Contraction

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Observation Table:

S No Manometric Reading Time for

x=___cm of water h1 h2 h = h1 – h2

1 2 3

Formulae:

t

xAQ tank

a =

( )21

w

Hg

c h-h1-S

Sh ×

=

( )222 d4

Aπ

=

2

a2

A

QV =

)V2.g.h(

VC

2c

2C

+=

Where,

Atank – Area of Measuring Tank (0.3 X 0.3 m2) x – Rise of water level for which time is measured(from the table above)

t – Time taken for x cm of water collection.

hc – head loss due to Sudden Contraction in Pipe

d2 – Pipe Diameter after Contraction (15mm or 0.015m)

g – Acceleration due to Gravity (9.81 m/s2)

V2 – Velocity of Water Flow after Contraction

A2 – Area of Smaller Pipe

Result Table:

S No hc Q V2 Cc

1 2 3

Average of CC = _________

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Procedure:

1. Make sure the Water in Sump Tank is free of any Oil Content.

2. Open all the Outlet Valves, Close all the Valves of Manometer and Start the Pump.

3. Close all Valves, except the Outlet Valve of the Pipe with Sudden Contraction to be

tested.

4. Open the Side Valves A and B of the Manometer.

5. Remove all the Air Bubbles from Manometer and Connecting Tubes by opening the Upper

Valves (C and D) of Manometer.

6. Adjust the Flow to get Suitable Readings.

7. Note down the Manometric Readings and time ‘t’ for height ‘x cm’ of water collection in

Measuring Tank.

8. Change the Flow Rate and take similar readings.


Note: While measuring the heads, slight variation may occur due to voltage changes, valves etc. in

such cases, average readings must be considered.

Precautions:






Result:

The Coefficient of Contraction for the given Pipe combination is found to be ________.

Applications:

Many times in a pipeline the flow needs to go through Pipes of different diameters. Whenever

a Sudden contraction exists in a pipe there is a minor loss taking place at the joint which results in

head loss and hence the overall Head Loss is found to be more than that calculated due to Darcy

Weisbach Equation. If we know the value of Cc, this extra loss can also be calculated and the piping

design can be done for the precise value of head loss.

Questions:

1. What is the meaning of GI?

2. What is Viscosity? Or State and explain Newton’s law of Viscosity.

3. Explain the different types of Major Losses in a Pipe Flow.

4. What is Darcy Weisbach Equation and what is its use?

5. What is Eddy Loss?

6. What is Stream line flow, Steady Flow, Uniform Flow, Laminar Flow?

7. What is a Stream Tube?

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Experiment No. 4

CALIBRATION OF VENTURIMETER

Aim:

To find the Coefficient of Discharge for the given Venturimeter and hence to calibrate it.

Apparatus Required:



3. A mono block pump with a valve in discharge pipe to control discharge.

4. The discharge pipe from pump gets divided into two pipes one holding a Venturimeter and

another holding an Orifice meter. Valves are provided at the ends to stop or allow discharge.

5. A differential manometer to measure pressure difference between two points.

6. Stop Watch to measure time.

Theory:

A Venturimeter is a device which is used for measuring the rate of flow of fluid through pipe

line. The pressure difference due to reduced cross-sectional area is proportional to Water Discharge.

So, if we know the Coefficient of Discharge we can determine the Water Discharge just by measuring

the pressure difference in the Throat and Inlet.

A Venturimeter consists of,

1. An Inlet Section followed by a Convergent Cone,

2. A Cylindrical Throat and

3. A gradually Divergent Cone.

Theoretical Discharge can be calculated using the following formula:

( )

/Secmaa

2gHaaQ 3

2

2

2

1

21

th =

where,

a1 – area of pipe or inlet section of Venturimeter

a2 – area of throat of Venturimeter

g – acceleration due to gravity, (9.81 m/s2)

H – the head difference between inlet and throat of Venturimeter.

Co - efficient of Discharge is the ratio of Actual discharge to the theoretical discharge as given

by the equation:

th

a

d Q

Q

dischargelTheoretica

dischargeActualC ==

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Observation Table:

S No Manometer Reading Time for x=__ cm water

discharge t (Sec) h1 h2 h = h1 – h2

1 2 3 4 5 6

Formulae:

1) Manometric Head

h1-S

SH

w

Hg ×

=

Where h is in meters

2) Theoretical Discharge:

( )

/Secmaa

2gHaaQ 3

2

2

2

1

21

th =

where, a1 – area of inlet section of Venturimeter = (πD2 / 4) m2

D – Diameter of pipe = 25 mm a2 – area of throat of Venturimeter = (πd2 / 4) m2

d – Diameter of the throat = 13.5 mm



Substituting the values of a1, a2 & g, the formula reduces to:

Qth = 662.84 x 10-6 x H

3) Actual Discharge:

t

xAQ tank

a =

where, x – Height of water considered

t – Time taken for the x height of water discharge

4) Co - efficient of Discharge:

th

ad

Q

Q

DischargelTheoretica

DischargeActualC ==

Calculation Table:

S No H Qa Qth Cd (Qa/Qth)

1 2 3 4 5 6

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Procedure:

All the necessary instrumentations along with its accessories are readily connected. It is just

enough to follow the instructions below:

1. Make sure the water in sump Tank is free of any oil content.

2. Open all the outlet valves and start the pump.

3. Open the outlet valve of the Venturimeter and close the valve of orifice meter.

4. Remove all the air bubbles from manometer and connecting pipes.

5. Adjust the flow at suitable rate.

6. Note down the manometric readings.

7. Close the gate valve of measuring tank & determine the time‘t’ for height ‘x cm’ of

water collection in measuring tank.

8. Change the flow rate and take similar readings.

Precautions:

1. Do not start the pump if the voltage is less than 180 V.

2. Do not forget to give electrical neutral & earth connections correctly.

3. Frequently (at least once in three months) grease / oil the rotating parts.

4. Initially, put clean water free from foreign material, and change once in three months.

5. At least every week, operate the unit for five minutes to prevent clogging of the moving parts.

Graphs:

Draw a graph of Actual Discharge Vs Theoretical Discharge and Find the Slop of the resultant

straight line.

Result:

1. The average co-efficient of discharge was calculated and found out to be _______.

2. The Slope of the Straight line in the curve is found to be __________.

Applications:

Venturimeter is used to measure Flow rate in pipelines carrying different fluids under pressure

where it is not possible to make use of a collecting tank and stop watch. Examples: Petroleum

pipelines, Water Pipelines etc.

In places like Dams Pressure needs to be retained for conversion to Mechanical Power and

hence a Venturimeter is a best replacement for Collecting Tank.

As the set up cost of a Venturimeter is high, it is only used where the losses have to be

maintained minimum, and cost is not a problem.

Questions:

1. What is the main Aim of the Experiment?

2. What are the Applications for Venturimeter?

3. What is the Working Principle of a Venturimeter?

4. What are the various Sections of a Venturimeter?

5. What are the Losses on account of Flow through a Venturimeter?

6. What is the Normal Range of Coefficient of Discharge for a Venturimeters?

7. What are the Precautions to be taken while performing the Experiment?

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Experiment No: 5

CALIBRATION OF ORIFICEMETER Aim:

To find coefficient of Discharge and hence Calibrate Orifice meter.

Apparatus Required:



3. A mono block pump with a valve in discharge pipe to control discharge.

4. The discharge pipe from pump gets divided into two pipes one holding a Venturimeter and

another holding an Orifice meter. Valves are provided at the ends to stop or allow discharge.

5. A differential manometer to measure pressure difference between two points.

6. Stop Watch to measure time.

Theory:

An ORIFICE METER is another simple device used for measuring the discharge through pipes.

Orifice meter also works on the same principle as that of Venturimeter i.e., by reducing the cross-

sectional area of the flow passage, a pressure difference between the two sections before and after

orifice is obtained and the measurement of the pressure difference enables the determination of the

discharge through the pipe. However, an orifice meter is a cheaper arrangement for discharge

measurement through pipes and its installation requires a smaller length as compared with

Venturimeter. As such where the space is limited, the orifice meter may be used for the measurement

of discharge through pipes.

An Orifice meter consists of,

1. An inlet section

followed by a

Sudden

Contraction,

2. A sudden enlargement

to the same

diameter as inlet.

Theoretical Discharge

can be calculated using the

following formula:

( )

/Secmaa

2gHaaQ 3

2

2

2

1

21

th =

where,

a1 – area of inlet section of Venturimeter

a2 – area of throat of Venturimeter


H – the head difference between the point just before orifice and at Vena Contracta.

Co - efficient of Discharge is the ratio of Actual discharge to the theoretical discharge as given

by the equation:

th

a

d Q

Q


dischargeActualC ==

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Observation Table:

S No Manometer Reading Time for x=____ cm water

discharge t (Sec) h1 h2 h = h1 – h2

1 2 3 4 5 6

Formulae:

1) Manometric Head

h1-S

SH

w

Hg ×

=

Where h is in meters

2) Theoretical Discharge:

( )/Secm

aa

2gHaaQ 3

22

21

21th

−=

where, a1 – area of inlet section of Venturimeter =________(πD2 / 4) m2

D – Diameter of pipe a2 – area of throat of Venturimeter =_______(πd2 / 4) m2

d – Diameter of the throat



Substituting the values of a1, a2 & g, the formula reduces to:

Qth = 610.67 x 10-6 x H

3) Actual Discharge:

t

xAQ tank

a =

where, x – Height of water considered

t – Time taken for the x height of water discharge

4) Co - efficient of Discharge:

th

a

d Q

Q


dischargeActualC ==

Calculation Table:

S No H Qa Qth Cd (Qa/Qth)

1 2 3 4 5 6

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Procedure:

1. Make sure the water in sump Tank is free of any oil content.

2. Open all the outlet valves and start the pump.

3. Open the outlet valve of the orifice meter and close the valve of Venturimeter.

4. Remove all the air bubbles from manometer and connecting pipes.

5. Adjust the flow at suitable rate.

6. Note down the manometric readings.

7. Close the gate valve of measuring tank & determine the time‘t’ for height ‘x cm’ of water

collection in measuring tank.

8. Change the flow rate and take similar readings.


Precautions:

1. Do not start the pump if the voltage is less than 180 V.

2. Do not forget to give electrical neutral & earth connections correctly.

3. There is no danger of water being not there in the sump tank, since the measuring tank is fitted

with overflow pipe.

4. Frequently (at least once in three months) grease / oil the rotating parts.

5. Initially, put clean water free from foreign material, and change once in three months.

6. At least every week, operate the unit for five minutes to prevent clogging of the moving parts.

Graphs:

Draw a graph of Actual Discharge Vs Theoretical Discharge and Find the Slop of the resultant

straight line.

Result:

1. The average co-efficient of discharge was calculated and found out to be _______.

2. The Slope of the Straight line in the curve is found to be __________.

Applications:

Orificemeter is used to measure Flow rate in pipelines carrying different fluids under pressure

where it is not possible to make use of a collecting tank and stop watch. Examples: Petroleum

pipelines, Water Pipelines etc.

In places like Dams Pressure needs to be retained for conversion to Mechanical Power and

hence a Orificemeter is a better replacement for Collecting Tank.

The Space and cost of setting up an Orificemeter is considerably less compared to

Venturimeter but its coefficient of discharge is less, so it is used at places where low cost is preferred

and Power loss is not a problem.

Questions:

1. What is the main aim of the experiment?

2. What is the working principle of an orificemeter?

3. What are the sections of an orificemeter?

4. What are the losses on account of flow through an orificemeter?

5. What is the normal co-efficient of discharge in an orificemeter?

6. What are the precautions to be taken while performing the experiment?

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Experiment No. 6

CENTRIFUGAL PUMP Aim:

To find the overall efficiency of a Centrifugal Pump and plot the following characteristics.

a. Hydraulic Efficiency (ηh) Vs Discharge

b. Overall Efficiency (ηo) Vs Discharge

Apparatus Required:

Stop Watch, Centrifugal pump test rig, which is a self – contained unit operated on

Recirculation Basis. The Centrifugal Pump, AC Motor, Sump Tank, Collecting Tank, Control Panel are

mounted on rigid frame work with anti-vibration mounts and arranged with the following provisions:

1. Energy Meter to measure Electrical Input Power to the AC motor using.

2. Pressure Gauges for recording the Discharge and Suction Pressures.

3. A discharge pipe fitted with a Valve to Control the Rate of Flow.

4. A Collecting Tank with Piezometer for measuring the Rate of Discharge.

5. A Sump flow Pipe with Valve to allow water flow back into the Sump Tank.

Theory:

In general, a pump may be defined as a Mechanical Device which, when interposed in a

pipe line, converts the Mechanical Energy supplied to it from some External Source into Hydraulic

Energy, thus resulting in the flow of liquid from Lower Potential to Higher Potential.

The Pumps are of major concern to most Engineers and Technicians. The Types of Pump vary

in Principle and Design. The selection of the pump for any particular application is to be done by

Understanding their Characteristics. The most commonly used Pump for Domestic, Agricultural and

Industrial Purposes are : Centrifugal Pumps, Reciprocating/Piston Pumps, Axial Flow (Stage Pumps), Air

Jet, Diaphragm and Turbine Pumps. These Pumps fall into classes of Rotodynamic, Reciprocating

(Positive Displacement), Fluid (Air) Operated Pumps.

In Centrifugal Pump the liquid is made to rotate in a Closed Chamber (Volute Casing), thus

resulting in the Continuous Flow. These Pumps compared to Reciprocating Pumps are Simple in

Construction, more suitable for handling Viscous, Turbid (muddy) Liquids. But, their Hydraulic Heads

per stage at low flow rates is limited, and hence not suitable for very high heads compared to

Reciprocating Pumps of same Capacity. But, still in most cases, this is the only type of Pump which is

being widely used for Agricultural Purposes.

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Observation Table:

S

No

Discharge Pressure

Head ‘Pd’ (kg/cm2)

Suction Vacuum

‘Ps’

(in mm of Hg)

Time taken for 50 lit

(10cm of tank)

water Discharge, t

(sec)

Time taken for 1

rev. of Energy

meter te (sec).

Calculations:

1. Discharge head

10Ph dd ×= m of water

2. Suction Head:

1000

×=

13.6Ph

s

s m of water

3. Total Head:

ht = hd + hs + 2m of water

4. Discharge:

t

xAQ tank

a = m3/s

5. Water power (or Output Power)

1000

.Q.hWP

tω= kW

Where,

ω – Specific Weight of water = 9810 N/m3.

Q – Discharge (m3/sec).

ht – Total head (m)

6. Electrical Input

Let time required for 10 rev. of energy meter disc be te-Sec.

Electrical Input Power, IP

eC t

3600

E

nIP ×= kW

Taking motor efficiency as 75% we have Input Shaft Power,

SP = IP x 0.75

7. Hydraulic Efficiency

100SP

WPh ×=η %

8. Overall efficiency

100IP

WPo ×=η %

Result Table

S

No ht Q WP IP oη SP hη

1. 2. 3. 4. 5.

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Procedure:

All the necessary instrumentations along with its accessories are readily connected. It is just

enough to follow the instructions below

1. Fill in the Sump Tank with clean water.

2. Open the priming nipple plug (at the top of pump) and pour water into it filling it up to the

nipple

3. Close the discharge valve.

4. Start the pump. As discharge valve is closed, no discharge will be observed, but discharge

pressure will be indicated. This is called Shut off head of the pump.

5. Slowly open the discharge valve, so that small discharge is observed.

6. Note down discharge head, suction vacuum, time required for 10 lit water discharge and 10

revolutions of energy meter disc.

7. Note down the observations at different valve openings.

8. Repeat the steps 3 to 7 for different speeds. Different speeds can be obtained by changing

the position of motor and belt for different pulley configurations.

Precautions:

1. Priming is must before starting the pump. Pump should never be run empty.

2. Use clean water in the sump tank.

3. Use all the controls and switches carefully.

4. Do not disturb the pressure gauge connections.

Graphs:

Main characteristics – Plot the following Graphs

a. Discharge vs Overall Efficiency

b. Discharge vs Hydraulic Efficiency

Result /Conclusion:

The overall efficiency for different speeds were calculated and graphs plotted.

Applications:

The most commonly used pumps for domestic, agricultural and industrial purposes are;

Centrifugal pumps. These pumps fall into the main class, namely, Rotodynamic pumps.

Questions:

1. What is meant by a Roto-dynamic machine?

2. What is meant by priming of a pump?

3. What energy is converted in a pump?

4. What types of fluids are pumped by centrifugal pumps?

5. What are the pumping characteristics of a centrifugal pump?

6. What is meant by efficiency of a pump?

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Experiment No: 7

PERFORMANCE TEST ON MULTI STAGE CENTRIFUGAL PUMP

Aim:

To find the overall efficiency of a Centrifugal Pump and plot the following characteristics.

c. Hydraulic Efficiency (ηh) Vs Discharge

d. Overall Efficiency (ηo) Vs Discharge

Apparatus Required:

Multi-Stage Centrifugal pump test rig, Stop Watch.

Introduction:

Centrifugal pumps are basically Roto-Dynamic Pumps, which develop Dynamic Pressures for

Liquids. In Centrifugal pumps, liquid in Impeller is made to rotate by external force, so that it is thrown

away from the Center of Rotation. As constant supply of fluid is needed at the center of rotation, its

supply can be taken from higher level.

Normally, head produced by a single impeller depends upon the peripheral speed of the

impeller. In order to produce higher heads, either rotational speed or diameter of the impeller has to

be increased, which increases stresses in the material of impellers. Hence, two pumps in series can be

used to produce higher heads. Now, this method is replaced by multistage pumps. In multistage

pumps, two or more impellers are arranged on a single shaft so that liquid discharged by first stage

impeller at certain head passes to the next stage impeller, where the head is increased till the liquid

finally enters into delivery pipe.

The unit consists of a two stage centrifugal pump driven by a 3-phase induction motor. An

energy meter provided measures electrical input to the motor and a measuring tank provided

enables to measure the discharge of the pump. A gate performance of the pump can be estimated

at various heads.

A 5 Stage Centrifugal Pump

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Observation Table:

S

No

Discharge

Pressure, Pd (kg/cm2)

Suction Vacuum,

Ps (mm of Hg)

Time for ___ lit

water (___cm of

tank) discharge,

tm (sec)

Time for n=___rev

of Energy meter, te (sec)

1. 2. 3. 4. 5.

Formulae:

1. Discharge head


2. Suction Head:

1000

13.6Ph ss

×= m of water

3. Total Head:


4. Discharge:

t

xAQ tank

a = m3/s


1000

W.Q.hWP t= kW

6. Electrical Input



eC t

3600

E

nIP ×= kW


SP = IP x 0.75


100SP

WPh ×=η %


100IP

WPo ×=η %

Result Table

S

No ht Q WP IP o

η SP hη

1. 2. 3. 4. 5.

Where,

W – Specific Weight of water = 9810 N/m3.



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Procedure:

1. Make sure the Sump tank is filled with water.

2. If the pump doesn’t start discharging water, open the Priming Nipple and pour water till the

casing is fully filled.

3. Open the discharge valve fully.

4. Start the pump. As the discharge valve is closed, no discharge will be observed, but the

pressure gauge shows some reading. This is called “shut off head” of the pump.

5. Now slowly open the discharge valve, so the small discharge is observed.

6. Note down the discharge head (by pressure gauge on discharge pipe) and suction vacuum.

7. Note down time required for 25 ltr water collection in measuring tank.

8. Note down the time required for 10 revolutions of energy meter.

9. Repeat the procedure by varying the discharge valve opening, and fill up the observation

table.

Precautions:

1. Priming is must before starting the pump. Pump should never be run empty.

2. Observe the direction of rotation of pump. If it is reverse, interchange any two of the 3

connections of motor.

3. Use clean water in the sump tank.

4. Use all the controls and switches carefully.

5. Do not disturb the pressure gauge connections.

6. Drain all the water after completion of experiment.

Graphs:

Operating characteristics – Plot the graph of Discharge vs Overall efficiency and Hydraulic

efficiency.

Result:

From the Operating Characteristics, it is noted that

a. Maximum efficiency occurs at the discharge of ….. m3/sec & is ……

b. Maximum power input to pump is … kW

c. Maximum discharge of pump is ….. m3/sec.

Applications:

As Multistage Pump works as 2 Pumps in series, it has capacity to develop very high heads

which is not possible for a Single Stage Pump. These Pumps find application where high Head is

required. The number of stages can be decided based on the requirement. However it has been

found that increasing the stages beyond limit reduces the efficiency drastically.

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Observation Table:

S No

Speed of

Pump, Np (in

rpm)

Discharge

Pressure Head

‘Pd’ (kg/cm2)

Suction

Vacuum ‘Ps’

(in mm of Hg)

Time for ___ lit water

(___cm of tank)

discharge, tm (sec)

Time for

n=___rev of

Energy meter,

te (sec)

1. 2. 3. 4. 5.

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Experiment No: 8

RECIPROCATING PUMP

Aim:

To find the overall efficiency of a Reciprocating Pump and plot the following characteristics.

a. Hydraulic Efficiency (ηh) Vs Discharge

b. Overall Efficiency (ηo) Vs Discharge

Apparatus Required:

Reciprocating pump test rig, stop watch.

The present Reciprocating Pump Test Rig is a self-contained unit operated on Closed Circuit

(Recirculation) Basis. The main components are singe acting Single Cylinder Reciprocating Pump, AC

Motor, Sump Tank, Collecting Tank, control Panel are mounted on rigid frame work with anti-vibration

mounts and arranged with the following provisions:

1. Stepped Cone Pulley arrangement to run pump at 3 different speeds and AC Motor.

2. To measure the input horse power to the pump using energy meter reading.

3. To measure the speed in rpm of the motor and the pump, separately.

4. To measure the delivery and suction heads using pressure and vacuum gauges separately.

(The delivery head pressure tapping is connected, upstream of delivery valve, and that of the

suction tapping downstream of suction valve).

5. To change the head and flow rate using control valves.

6. To measure the discharge using collecting tank fitted with tank level indicator.

Specifications:

Reciprocating Pump : 30 cm core, stroke length 20mm, double acting with air vessel on

discharge side suction Ф 19mm, discharge Ф 12.7mm.

AC Motor : AC Motor, 1 HP, speed variations controlled by a stepped cone

pulley.

Measuring (Metering) Tank : 400mm x 400mm x 450mm height provided with gauge tbe and

swiveling joint in piping for diverting the flow into measuring tank r

sump tank.

Sump tank : 600mm x 900mm x 600mm height.

Measurements

Pressure gauge : 0-7 Kg/cm2 for discharge pressure.

Vacuum gauge : 0-760 mm Hg suction vacuum

3 Ph Energy meter for motor input measurements.

Theory:

In general, a pump may be defined as a mechanical

device which, when interposed in a pipe line, converts the

mechanical energy supplied to it from some external source

into hydraulic energy, thus resulting in the flow of liquid from

lower potential to higher potential.

The pumps are of major concern to most Engineers and

Technicians. The types of pump vary in principle and design.

The selection of the pump for any particular application is to

be done by understanding their characteristics. The most

commonly used pumps for domestic, agricultural and

industrial purposes are: Centrifugal, Piston, Axial Flow (Stage

pumps), Air Jet, Diaphragm and Turbine pumps. Most of these

pumps fall into the main class, namely, Rotodynamic,

Reciprocating (Positive Displacement), Fluid (Air) operated

pumps.

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Calculations:

1. Discharge head


2. Suction Head:

1000

×=

13.6Ph

s

s m of water

3. Total Head:


4. Discharge:

t

xAQ tank

a = m3/s


1000

.h.QWP taω

= kW

Where,

ω – Specific Weight of water = 9810 N/m3.



6. Electrical Input



eC t

3600

E

nIP ×= kW


SP = IP x 0.75


100SP

WPh ×=η %


100IP

WPo ×=η %

Graphs – Plot the following graphs for the Pump.

Discharge vs Overal Efficiency

Discharge vs Hydraulic Efficiency

Result Table

S

No ht Q WP IP o

η SP hη

Optional Calculations

1. Coefficient of discharge of pump

t

ad

Q

Q=C

2. Slip

x100Q

Q-QSlip

t

at=

Where Qa is Actual Discharge and Qt the

Theoretical Discharge

60

rpm) (in N x Volume SweptQ t =

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Procedure:

All the necessary instrumentation along with its accessories are readily connected. It is just enough

to follow the instructions below:

1. Fill in the sump tank with clean water.

2. Full up the air vessel for about 2/3rd capacity.

3. Open the gate valve in the discharge pipe of the pump fully.

4. Close the gate valve and drain valve of the measuring tank.

5. Check nut bolts & the driving belt or proper tightening.

6. Divert the outlet pipe into funnel and slowly increase the pump speed, slightly close the

discharge valve. Note down the various readings in the observations table. Repeat the

procedure for different gate valve openings. Take care that discharge pressure does not rise

above 4 Kg/cm2.

7. Change the speed and take readings for different gate valve openings. Repeat the

procedure for different speeds and complete the observation table.

Precautions:

1. Operate all the controls gently.

2. Never allow to rise the discharge pressure above 4kg/cm2

3. Always use clean water for experiment.

4. Before starting the pump ensure that discharge valve is opened fully.

Result /Conclusion:

The overall efficiency for different speeds were calculated and graphs plotted.

1. For default belt position, the overall efficiency was found out to be _________.

Applications:

These are called Positive Pumps because there is a fixed amount of fluid flow for a complete

rotation of crank shaft. As there is no fluid flow for zero displacement and vice versa the Head

developed is proportional to the load applied. These pumps find application in:

1. To drill oil from deep wells.

2. To pump any liquid, which is free from debris.

3. To pump precise amounts of fluids. Ex: Petrol Pumps

Questions:

1. What is the main aim of the experiment?

2. What is meant by a positive displacement pump?

3. What types of fluids are pumped by Reciprocating pumps?

4. What are the pumping characteristics of a Reciprocating pump?

5. What is the normal efficiency of a Reciprocating pump?

6. What are the normal precautions to be taken when operating a pump?

7. What is the function of air vessel?

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Experiment No: 9

PELTON WHEEL TURBINE Aim:

To determine the performance characteristics of Pelton wheel turbine under constant head

and constant speed.

Apparatus Required:

Pelton wheel turbine test rig.

Construction:

The actual experimental set-up consists of a Sump Tank, Centrifugal pump, Delivery pipe and

Turbine unit arranged in such a way that the whole unit works as re-circulating water system. The

centrifugal pump set supplies water from the sump tank to the turbine through a Venturimeter. The

flow rate can be changed by control valve. The water after impinging on the turbine unit falls back

into the Sump Tank.

The loading of the turbine is achieved by rope brake drum connected to spring balances. The

turbine speed is measured with a Tachometer, head on the turbine is measured with pressure gauge

and the discharge rate is calculated with the help of Pressure readings at Venturimeter.

Supply Pump / Motor Capacity : 15 hp, 3 ph, 440V, 50 Hz AC.

Mean Dia. of runner : 280 mm

No. of buckets : 20

Dia. Of Nozzle : 30 mm

Runaway Speed : ________

Max Head : ________

Loading : Brake Drum (radius : 30 cm)

Provision : Venturimeter with gauges for Flow Rate

Theory:

Hydro-Power is one of major cheap source of power available on earth, and hence it is widely

used for generation of electric power world wide. Water stored in the Dam contains potential energy.

This is utilized to run turbine, which then drives a generator. The output from the generator can be

transmitted to the areas of electric power requirement.

Turbines are basically of two types, viz. Impulse turbines

and Reaction turbines. In impulse turbines, water coming from

high head acquires high velocity. The high velocity water jet

strikes the buckets of the turbine runner and makes it to rotate by

impact force. In reaction turbine, total head of water is partly

converted into velocity head as it approaches turbine runner

and it fills the runner and pressure of water gradually changes as

it flows through runner. In impulse turbine, the only turbine used

now-a-days is Pelton Wheel Turbine. In reaction turbines, Francis

Turbine and Kaplan Turbine are the examples.

The Pelton wheel turbine consists of a runner mounted

over the main shaft. Runner consists of buckets fitted to the disc.

The buckets have a shape of double ellipsoidal cups. The runner

is encased in a casing provided with a Perspex window for

viewing the turbine. A nozzle fitted in the side of casing directs

the water jet over the 'Splitter' or center ridge of the buckets. A

spear operates inside the nozzle to control the water flow. On the other side of the shaft, a rope brake

is mounted for loading the turbine.

Impulse turbines convert all the energy of Water into Kinetic Energy at the nozzle. The jet

impinges on the turbine's curved blades and gets diverted (by about 160o). The resulting change in

momentum (impulse) causes a force on the turbine blades.

All the Pressure/Potential Energy is converted to kinetic energy by the nozzle and focused on

the turbine. No pressure change occurs at the turbine blades, and the turbine doesn't require a

housing for operation. Newton's second law lets us calculate transfer of energy for impulse turbines.

Impulse turbines are most often used in very high head applications, but the discharge used is less.

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Observation Table:

Table I : Constant Speed Characteristics

Method : By keeping Butterfly Valve position fully open and changing the spear valve position to

get constant speed.

‘N’ in

rpm

Spear valve

position

Pressure ‘P’

in kg/cm2

Diff Head over

the Venturimeter

‘h’ in meters

‘F1’

kgf

‘F2’

kgf Remarks

Table II : Constant Head Characteristics

Method: 1) Spear rod at fixed position

2) Butterfly Valve fully open &

3) Change Brake Drum load

Turbine speed ‘N’ in

rpm

Pressure

“P” in kg /

cm2

Diff Head over the

Venturimeter ‘h’ in

meters

‘F1’

kgf

‘F2’

kgf

Remarks

Observation Table:

Table I : Constant Speed Characteristics

Turbine

Speed

‘N’ rpm

Net head

on Turbine

‘H’ m.

Discharge

(flow rate)

‘Q’ m3/sec

HPhyd BHP % ηtur % of Full

Load Remarks

Table – II : Constant Head Characteristics

Turbine

Speed ‘N’

in rpm

Net head

on Turbine

‘H’ m.

Discharge

(flow rate) ‘Q’

in m3/Sec

HPhyd BHP % ηtur Remarks

Unit quantities under unit head

(Calculations based on Table of Calculations – II)

Net head on

turbine “h” m.

unit speed

“nu”

unit power

“pu”

unit discharge

“qu”

specific

speed “ns” % ηtur remarks

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Procedure:

1. Make sure the connections are properly done: Motor unit connected to 3 ph, 440V, 30A, electrical

supply, with neutral and earth connections and ensure the correct direction of pump-motor unit.

2. Keep the Butterfly valve and spear valve closed.

3. Keep the Brake Drum loading at minimum.

4. Press the green button of the supply pump starter. Now the pump picks-up the full speed and

becomes operational.

5. Slowly, open the spear valve so that the turbine rotor picks up the speed and attains maximum at

full opening of the valve.

a) To obtain constant speed characteristics:

1. Keep the Butterfly valve opening at maximum

2. For different Brake Drum loads on the turbine, change the spear rod setting, between

maximum and minimum so that the speed is held constant.

3. Tabulate the results as per Table - I .

4. The above readings are utilized for drawing constant speed characteristics Viz.,

b. Percentage of full load V/s efficiency.

c. Efficiency and BHP V/s discharge characteristics.

b) To obtain constant head characteristics:

1. Keep the spear rod setting and Butterfly Valve setting at maximum.,

2. For different Brake load, note down the speed, Head over notch

and tabulate the results as given in Table – II.

c) To obtain run-away speed characteristics:

1. Keep the load on the brake , zero.

2. Keep spear rod and Butterfly Valve at maximum .

Note:

Run – away speed is also influenced by the tightening in gland packing of the turbine shaft. More

the tightness, less the run – away speed.

d) Performance under unit head – Unit quantities:

In order to predict the behavior of a turbine working under varying conditions and to facilitate

comparison between the performances of the turbines of the same type but having different outputs

and speeds and working under different heads, it is often convenient to express the test results in terms

of certain unit quantities.

From the output of a turbine corresponding to different working heads (Table of Calculations –

II) it is possible to compute the output which would be developed if the head was reduced to unit

(say 1 m..); the speed being adjustable so that the efficiency remains unaffected.

a. Unit Speed, H

NNu =

b. Unit power, 3/2u

H

PP =

c. Unit Discharge, H

QQu =

d. Specific Speed,

The specific speed of any turbine is the speed in rpm of a turbine geometrically similar to the actual

turbine but of such a size that under corresponding conditions it will develop 1 metric horse power

when working under unit head (i.e., 1 meter.).

The specific speed is usually computed for the operating conditions corresponding to the maximum

efficiency.

5/4u

H

PNN =

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Calculations:

1. Net/Working head on the Turbine:

H=10 x Pd

2. Discharge (Flow rate)of water through the Turbine,

2

2

2

1- AA

2xgxHxAxACQ 21d

a = m3/sec

Where,

dC -Coefficient of Discharge for Venturimerter = 0.9

1A - Area of Cross Section of Pipe

2A - Area of Cross Section of Venturimeter Throat

g – Acceleration due to gravity (9.81 m/s2)

H – Pressure head (Calculated above)

3. Hydraulic Power (Input to the Turbine):

1000

.HW.QHP a=

Where,

W – Specific Weight of water = 9810 N/m3.


H – Total head (m)

4. Brake Power (Output from the turbine),

)FF(60

gNDBP

21×

×××=π

Where,

F1 and F2 are the spring balance readings in kgf

D – Diameter of the Brake Drum (30 cm)

5. Turbine Efficiency (Output from the turbine),

100HP

BP×=η

6. Unit quantities – under unit head,

a. Unit Speed, HN/Nu =

b. Unit power, 3/2

u BHP/HP =

c. Unit Discharge, HQ/Qu =

7. Specific speed,

5/4u

H

BPNN =

Obtained at maximum efficiency.

8. Percentage Full load = 100.

×BPloadMax

BPloadPart (at any particular speed.)

Graph:

Constant head characteristics

1. Unit discharge (Qu) vs. Unit speed (Nu).

2. Unit power (Pu) vs. Unit speed (Nu).

3. Percentage efficiency (%η) vs. Unit speed (Nu).

Constant speed characteristics

1.Percentage efficiency (%η) vs. percentage full load.

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Precautions:

1. Do not start pump set if the supply voltage is less than 300 V (phase to phase voltage).

2. Do not forget to give electrical earth and neutral connections correctly. Otherwise, the

RPM indicator gets burnt if connections are wrong.

3. Frequently, at least once in three months, grease all visual moving parts.

4. Initially, fill-in the tank with clean water free from foreign material. Change the water

every six months.

5. At least every week, operate the unit for five minutes to prevent any clogging of the

moving parts.

6. To start and stop the supply pump, always keep gate valve closed.

7. It is recommended to keep spear rod setting at close position before starting the turbine.

This is to prevent racing of the propeller shaft without load.

8. In case of any major faults, please write to manufacturer, and do not attempt to repair.

Result /Conclusion:

The unit head and other quantities were calculated from the knowledge of constant head

characteristics and the curves were drawn. Similarly the constant speed characteristics were

calculated and the percentage efficiency vs. percentage full load was drawn.

Applications:

The basic force used for driving Pelton wheel results from the Impact of jet on the blades. High

Heads are required to produce jets with more Impact Force. Hence these turbines are used in Hydro-

Electric Power generation when High Head is available in the Reservoir.

Questions:

1. On what principle the Pelton wheel turbine works?

2. What is the shape of buckets in Pelton wheel turbine?

3. What is the clearance angle of the buckets? State why it is not 1800?

4. Define unit quantities and specific speed.

5. Why multiple jets are used in Pelton wheel turbine?

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fm hm lab manual aug 2011

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