Mach Number

  • Differentiate between various processes of expansion and compression

  • Determine the sonic velocity in a fluid.

  • Describe the effect of Mach number in flow.

The local speed of sound in an ideal gas is given by:

\[c = \sqrt{kRT}\]

c = local speed of sound
k = ratio of specific heats = \(\dfrac{c_p}{c_v}\)
R = specific gas constant = R /(molecular weight)
T = absolute temperature
Mach number is defined as the ratio of the particle (local) speed to the (local) speed of sound. The Mach number can be calculated by:

\[Ma =\dfrac {u}{c}\]

Ma is the Mach number
u is velocity of the flow and
c is the speed of sound at the given temperature

Solved Examples

Solved Example:


Mach number is significant in:

Correct Answer: A