1. An impulse air turbine rotor with a blade speed (U) of 300 m/s is measured to have a relative rotor inlet velocity (W_1) of 750 m/s at an angle of 69 degrees and an outlet relative velocity (W_2) of 660 m/s. Th temperature and pressure in the rotor are 375 K, 0.83 bar. Calculate the rotor efficiency, rotational speed and power output if it has a mean blade diameter of 220 mm, a blade length of 16,, and if it has 360 degrees of full length nozzles.
At the inlet to a reaction air turbine nozzle, the total pressure and total temperature are 7,39 bar, 1240 K.
a) If the nozzle has an efficiency of 87% and if the nozzle exit/rotor inlet pressure is 4,1 bar, calculate the nozzle exit velocity (C_1).
b) If the nozzle exit angle is 65 degrees and if the rotor speed is 390 m/s, calculate the relative rotor inlet velocity (W_1).
c) If the rotor has an efficiency of 84% and an exit pressure of 1,9 bar, calculate the rotor exit relative velocity (W_2).
d) Sketch the complete velocity diagrams with approximate blade shapes.
Notations and assumptions:
[ ]* = total features (like p*, T*)
cp = specific heat at constant pressure (for air at low temperatures we will take
cp = 1 kJ/kg.K and for high temperature
cp = 1.1 kJ/kg.K)
k = ...
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