1) A gas turbine has an overall pressure ratio of 5;11 and a maxi¬mum cycle temperature of 550°C. The turbine drives the compressor and an electric generator, the mechanical efficiency of the drive being 97%. The ambient temperature is 20`C and the isentropic efficiencies of the compressor and turbine are 0.8 and 0.83 respectively. Calculate the power output in kilowatts for an air flow of 15 kgjs. Calculate also the thermal efficiency and the work ratio. Neglect changes in kinetic energy, and the loss of pressure in the combustion chamber.
2) In a marine gas turbine unit a high-pressure stage turbine drives the compressor, and a low-pressure stage turbine drives the propeller through suitable gearing. The overall pressure ratio is 4/1, and the maximum temperature is 650°C. The isentropic efficiencies of the compressor, H.P. turbine, and L.P. turbine, are 0-8, 0.83, and 0.85 respectively, and the mechanical efficiency of both shafts is 98%. Calculate the pressure between turbine stages when the air intake conditions are 1.01 bar and 25°C. Calculate also the thermal effi-ciency and the shaft power when the mass flow is 60 kg/s. Neglect kinetic energy changes, and the pressure loss in combustion.
3) For tae unit of problem 2, calculate the thermal efficiency obtainable when a heat exchanger is fitted. Assume a thermal ratio of 0-75. (23.4%)