A multi-stage gas turbine is to be designed with impulse stages,and is to operate with an inlet pressure and temperature of 6 barand 900 K, and an outlet pressure of 1 bar. The isentropicefficiency of the turbine is likely to be 85 per cent. All thestages are to have a nozzle outlet angle of 15 degrees, equal inletand outlet blade angles, a mean blade speed of 250 m/s and equal 5kJ/kg K o inlet and outlet gas velocities. Estimate the number ofstages required. Assume cp 1.15 kJkg K and y 1.333.
[Suggested Answer: 2.54 stages (practically 3 stages)
