A model jet engine is shown with a series of processes at steady-state-steady-flow operation. Air enters the 1.0 m diameter inlet at high speed at section (1). The air then flows through a compressor (1 2) and a heating chamber (23). Hot, high-pressure air expands through a turbine (34) and finally the flow exits a nozzle (4 5), with very high velocity at section (5). The turbine power is exactly equal to that needed to drive the compressor. Heat transfer is negligible except for process (23); the heater takes the place of a combustion chamber. The air behaves as an ideal gas. Due to the high temperature use the tabulated h(T) values. The processes ARE NOT quasi-equilibrium nor polytropic. The flow areas are different for each cross-section. Find the Temperatures at (2) and (4), external heat transfer rate, 2Q3 (kJ/s) and nozzle exit diameter, D5 (m).
For air R = Ru/M = 0.287 kJ/kg-K
BUT
DO NOT ASSUME cp = constant
State p T V ke z
kPa K m/s kJ/kg m _
1 100 300 200 20 5000
2 1000 low 0 5000
3 960 2000 low 0 5000
4 300 low 0 5000
5 100 900 800 320 5000