Question

1.      Air enters a converging-diverging nozzle with a total pressure of 1100 kPa and a total temperature of 127°C. The exit area to throat area ratio is 1.8. The throat area is 5 cm². The velocity at the throat is sonic and the diverging section acts as a nozzle. The diverging section is now acts as a supersonic nozzle. Assume that a normal shock stands in the exit plane of the nozzle. Determine the following:

a.       The static pressure and temperature

b.       The total pressure just downstream of the normal shock

2.      Air approaches a diffuser of a turbojet engine with a pressure of 20 kPa at a Mach number of 2. A normal shock occurs at the inlet of the channel. The exit to inlet area ratio is 3. Determine the following:

a.       The loss of total pressure

b.      The Mach number at the exit

3.      Determine the diffuser efficiency if the shock is:

a.       At the inlet

b.      At the exit

Answer 1