Answer Happy

Question 3 A turbojet aircraft is flying at 850 km/h at 10700 m where the pressure and temperature of the atmosphere are 0.24 bar and -50°C respectively. The compressor pressure ratio is 12/1 and the maximum stagnation temperature in the cycle is 900°C. The combustion efficiency is 100% and there is no loss in the mechanical drive connecting the turbine shaft to the compressor. The cycle is shown in Figure Question 3. Calculate: (1) the actual temperature and pressure at the exit of the nozzle. (15 marks) (ii) the actual gas velocity at the nozzle exit and hence the mass flow rate through the nozzle. (5 marks) (ii) the thrust developed and the thrust-specific fuel consumption (5 marks) T -P > 4 3 2s P Sss Is -P a S Figure Question 3

Use the following information: stagnation isentropic efficiency of diffuser 0.9; stagnation isentropic efficiency of compressor 0.9; stagnation pressure loss in the combustion chamber 0.14 bar; calorific value of fuel 43300 kJ/kg; stagnation isentropic efficiency of turbine 0.92; stagnation isentropic efficiency of nozzle 0.92; nozzle outlet area 0.08 m²; Cp and y for the compression process 1.005 kJ/kg.K and 1.4; Cp and y for the combustion and expansion processes 1.15 kJ/kg-K and 1.333; Assume that the nozzle is convergent