chapter 12 edited - universiti teknologi malaysiasyahruls/resources/skmm2323/4-turbomachiner… ·...
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Turbomachinery
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Turbomachines are the commonly employed devices that either supply or extract energy from a flowing fluid by means of rotating propellers or vanes.
A turbopump/pump adds energy to a system, with the result that the pressure is increased.
A turbine extracts energy from a system and converts it to some other useful form, typically, to electric power.
A wind turbine converts the energy contained in the natural movement of atmospheric air into useful electricalpower.
12.1 Introduction
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Turbopump: Consists of two major parts—an impeller and the pump housing.
Common types of pumps are radial flow, mixed flow, and axial flow.
12.2 Turbopumps
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In a radial-flow pump, the impeller vanes are commonly curved backward and the impeller is relatively narrow.
12.2 Turbopumps
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Radial-Flow PumpsA radial-flow, or centrifugal, pump is designed to deliver relatively low discharge at a high head.
To construct a simplified theory for the radial-flow pump, it is necessary to neglect viscosity and to assume idealized two-dimensional flow throughout the impeller region.
12.2 Turbopumps
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12.2 Turbopumps
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12.2 Turbopumps
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12.2 Turbopumps
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12.2 Turbopumps
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Head-Discharge Relations: Performance CurvesBrake power: Power delivered to the impeller
12.2 Turbopumps
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12.2 Turbopumps
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Axial- and Mixed-Flow PumpsAn axial-flow pump produces relatively large discharges at low heads.
If there is no prerotation
12.2 Turbopumps
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12.2 Turbopumps
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12.2 Turbopumps
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12.2 Turbopumps
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12.2 Turbopumps
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12.2 Turbopumps
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net positive suction head:
12.2 Turbopumps
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Design requirement for a pump:
12.2 Turbopumps
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12.2 Turbopumps
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Dimensionless Coefficients
12.3 Dimensional Analysis and Similitudefor Turbomachinery
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The discharge, head, and power coefficients are used to form the dimensionless performance curves.
12.3 Dimensional Analysis and Similitudefor Turbomachinery
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12.3 Dimensional Analysis and Similitudefor Turbomachinery
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12.3 Dimensional Analysis and Similitudefor Turbomachinery
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12.3 Dimensional Analysis and Similitudefor Turbomachinery
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Similarity Rules:Similarity rules relate variables from a family of geometrically similar turbomachines, or are used to examine changes in variables for a given machine.
12.3 Dimensional Analysis and Similitudefor Turbomachinery
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12.3 Dimensional Analysis and Similitudefor Turbomachinery
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12.3 Dimensional Analysis and Similitudefor Turbomachinery
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Specific speed: Dimensionless number that characterizes a turbomachine at maximum efficiency.
12.3 Dimensional Analysis and Similitudefor Turbomachinery
12.3 Dimensional Analysis and Similitudefor Turbomachinery
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12.3 Dimensional Analysis and Similitudefor Turbomachinery
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Matching Pumps to System DemandSystem demand curve:
The intersection of the system demand curve with the pump head-discharge curve specifies the operating head and discharge.
12.4 Use of Turbopumps in Piping Systems
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Pumps in Parallel and in Series
Overall efficiencyof pumps in parallel is
12.4 Use of Turbopumps in Piping Systems
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12.4 Use of Turbopumps in Piping Systems
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12.4 Use of Turbopumps in Piping Systems
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12.4 Use of Turbopumps in Piping Systems
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12.4 Use of Turbopumps in Piping Systems
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In contrast to pumps, turbines extract useful energy from the water flowing in a piping system.
Runner: Moving component of a turbine.
Reaction turbine: Turbine using both flow energy and kinetic energy.
Impulse turbine: The flow energy is converted into kinetic energy through a nozzle before the liquid impacts the runner.
12.5 Turbines
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In reaction turbines, the flow is contained in a volute that channels the liquid into the runner. Adjustable guide vanes (also called wicket gates) are situated upstream of the runner.
12.5 Turbines
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12.5 Turbines
12.5 Turbines