Question

Select the correct statement for a Mach wave.

(a) M > 1

(b) \(\frac {P_2}{P_1}\)=0.528

(c) \(\frac {T_2}{T_1}\)=1

(d) \(\frac {\rho_2}{\rho_1}\)=∞

I got this question in quiz.

Origin of the question is Flow Compressible topic in portion Normal Shock Waves of Aerodynamics

Answer 1

Correct choice is (c) \(\frac {T_2}{T_1}\)=1

For explanation: A Mach wave is a normal shock wave of diminishing strength. It occurs for M=1 upstream. Then downstream M=1 also. And all the ratios are equal to 1, i.e \(\frac {P_2}{P_1}\)=1, \(\frac {T_2}{T_1}\)=1, \(\frac {\rho_2}{\rho_1}\)=1. This can be found by calculation when we put m=1. The properties across Mach wave do not change.