Sunday, August 29, 2010

How to calculate the Mach Number?

Assuming air to be an ideal gas, the formula to compute Mach number in a subsonic compressible flow is derived from Bernoulli's equation for M<1:[3]



where:

\ M is Mach number
\ q_c is impact pressure and
\ P is static pressure
\ \gamma is the ratio of specific heat of a gas at a constant pressure to heat at a constant volume (1.4 for air).

The formula to compute Mach number in a supersonic compressible flow is derived from the Rayleigh Supersonic Pitot equation:



where:

\ q_c is now impact pressure measured behind a normal shock.

Courtesy:Wikipedia,Wiki Dictionary,NASA-USA

0 comments:

Post a Comment