A model jet engine is shown with a series of processes at steady-state-steady-fl

ID: 1861738 • Letter: A

Question

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 (3

4) and finally the flow exits a nozzle (4 5), with very high velocity at section (5).

NOTE: 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.

Findthe 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

Any Help gets 5 stars!!!

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