Question

What happens to the coefficient of pressure in a supersonic flow for an increase in Mach number?

(a) Increases

(b) Decreases

(c) Remains unaffected

(d) First increases then decreases

I had been asked this question during an online interview.

This interesting question is from Application to Supersonic Airfoils topic in portion Subsonic Compressible Flow over Airfoils : Linear Theory, Linearized Supersonic Flow of Aerodynamics

Answer 1

Right choice is (b) Decreases

The best I can explain: For linearized supersonic flow, the coefficient of pressure is inversely proportional to \(\sqrt {M_∞^2-1}\). Thus, when the Mach number increases, the coefficient of pressure decreases. This in contrast to the trend followed by the subsonic flow where an increasing Mach number results in decreasing coefficient of pressure.