Pelton Wheel Turbine
ME413-Experiment #2 Performance Characteristics of Pelton Wheel (Impulse Turbine)
Purpose: To investigate typical performance characteristics of an impulse turbine.
Apparatus: Armfield Pelton Turbine, Armfield Hydraulics Bench and digital tachometer.
Sketch a labeled schmematic diagram of the apparatus.
Theory and Definitions:
(Ref. Munson/Young/Okiishi A Brief Introduction to Fluid Mechanics, 3/e, p. 479)
1. Ideal Power and efficiency
From 1-D energy equation, derive the ideal (inviscid flow) power output of an impulse turbine in terms of the flow rate and jet velocity. Review the definition of output power of a rotating shaft in terms of the torque and rotation speed. The turbine efficiency is simply defined as the ratio of actual power to ideal power of the turbine.
2. Dimensionless Coefficients
Review the definitions of flow coefficient, pressure coefficient and power coefficient.
Procedure
1 Turn on the pump on the hydraulic bench and fully open the control valve.
2 With the friction belt on the brake disk completely disengaged, adjust the flow rate to obtain a pressure head of about 5 m at turbine inlet, as indicated by the pressure gage at the inlet.
3 Tighten the friction belt on the brake disk so that the difference in the tensions of the two spring balances is about 1 N. Read the tachometer to obtain the rotation speed.
4 Repeat step 3 until the maximum on the spring balance is reached, or the rotation speed is zero.
5 Disengage the friction belt and adjust the flow rate so that the pressure head at the inlet is about 10 m. Repeat steps 3 and 4.
6 Repeat with a inlet pressure head of 15 m and 20 m.
Results:
1. Compute and plot the torque, power output, and turbine efficiency against rotation speed for each inlet pressure head.
2. Compute the flow coefficient, pressure coefficient and power coefficient and plot them on the same graph.
Conclusion:
Is the scaling law for turbomachine verified?
Purpose: To investigate typical performance characteristics of an impulse turbine.
Apparatus: Armfield Pelton Turbine, Armfield Hydraulics Bench and digital tachometer.
Sketch a labeled schmematic diagram of the apparatus.
Theory and Definitions:
(Ref. Munson/Young/Okiishi A Brief Introduction to Fluid Mechanics, 3/e, p. 479)
1. Ideal Power and efficiency
From 1-D energy equation, derive the ideal (inviscid flow) power output of an impulse turbine in terms of the flow rate and jet velocity. Review the definition of output power of a rotating shaft in terms of the torque and rotation speed. The turbine efficiency is simply defined as the ratio of actual power to ideal power of the turbine.
2. Dimensionless Coefficients
Review the definitions of flow coefficient, pressure coefficient and power coefficient.
Procedure
1 Turn on the pump on the hydraulic bench and fully open the control valve.
2 With the friction belt on the brake disk completely disengaged, adjust the flow rate to obtain a pressure head of about 5 m at turbine inlet, as indicated by the pressure gage at the inlet.
3 Tighten the friction belt on the brake disk so that the difference in the tensions of the two spring balances is about 1 N. Read the tachometer to obtain the rotation speed.
4 Repeat step 3 until the maximum on the spring balance is reached, or the rotation speed is zero.
5 Disengage the friction belt and adjust the flow rate so that the pressure head at the inlet is about 10 m. Repeat steps 3 and 4.
6 Repeat with a inlet pressure head of 15 m and 20 m.
Results:
1. Compute and plot the torque, power output, and turbine efficiency against rotation speed for each inlet pressure head.
2. Compute the flow coefficient, pressure coefficient and power coefficient and plot them on the same graph.
Conclusion:
Is the scaling law for turbomachine verified?