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