# Turbomachinery: Impulse & Reaction Turbines

Question 4: An impulse air turbine has a total (on static) inlet pressure and temperature of 11,25 bar, 600 degrees K and exhausts to the atmosphere at 0.91 bar. The nozzle efficiency is 87% and its exit angle is 71 degrees. The rotor efficiency is 65%. If the blade speed if 190 m/s at the mean radius of 12cm, calculate the power output for full admission to the 2cm long rotor blades.

Question 5: It has been decided to use the following velocity diagrams for a STEAM reaction turbine stage which is expected to have a nozzle and rotor efficiency of 80% when the stage inlet total ((not static) pressure and temperature are 17 bar, 400 degrees C. Using the small segment of the enthalpy-entropy chart for steam that is suppled, plot the hs diagram for the nozzle and rotor and hence determine the outlet pressures of each.

Question 6: It has been decided to use the following velocities for a reaction turbine stage which is expected to have a nozzle efficiency of 90% and a rotor efficiency of 85% when the stage inlet total (not static) pressure and temperature are 5 bar, 1050 K. Calculate the as yet known velocities and then determine the specific work output and the outlet pressure from the rotor.

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#### Solution Preview

Notations and assumptions:

[ ]* = total features (like p*, T*)

cp = specific heat at constant pressure (for air at low temperatures we will take cp ...

#### Solution Summary

THis solution includes complete step-by-step calculations and answers. The explanation is 683 words. Illustrations are used for the geometry of the velocities for (1) through (3) and the thermodynamic analysis for (1) and (2).