Professor Ian Eames
Coursework Assignment 3
State any assumptions that you use in your analysis and references to any material
you use. Submission is either via Word document or pdf only.
Make use of a compressible flow calculator (eg
1. A tank of compressed air with initial pressure 0 = 500 kPa at ambient temperature
0 = 293K is opened rapidly. The outlet is modelled as a converging-diverging
The tank and nozzle are characterised by cross-sectional areas 1, 2, 3 and 4 at
the points 1, 2, 3 and 4 along the tank. The area ratios are related by
The back pressure is = 100 kPa.
The mass flow rate of air escaping the nozzle is 1 kg s−1:
a) Sketch the variation of the Mach number along the axis of the tank (from inside) to
the nozzle exit.
b) Estimate the thrust force exerted by the exit flow.
2. Supersonic inlet buzz is a serious problem for supersonic jet engines. Describe
a) how is buzz generated,
b) how is buzz reduced.
Illustrate your discussion with typical numerical values and suitable references. The
word limit for the whole of question 2 is 300 words.