Page 129 - 48Fundamentals of Compressible Fluid Mechanics
P. 129
5.3. THE MOVING SHOCKS 91
Substituting equations (5.26) and (5.25) into equation (5.65) results in
(5.66)
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%
%
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%
When the pressure ratio is approaching infinity (extremely strong pressure ratio)
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(5.67)
What happened when a gas with Mach number larger than the maximum
Mach number possible is flowing in the tube? Obviously the semi steady state
described by moving shock cannot be sustained. And similar phenomenon to the
choking in nozzle and later in internal pipe flow is obtained. The Mach number is
reduced to the maximum value very rapidly. Or, a stationary shock occurs as it will
shown in chapters on internal flow.
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of maximum values of the shock-chocking phenomenon.
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Example 5.2:
A shock is moving at a speed of 450 [m/sec] in a stagnated gas at pressure of 1
[Bar] and temperature of 27
C. Compute the pressure and temperature behind the
shock. Assume the specific heat ratio is 1.3.
SOLUTION
It can be noticed that the gas behind the shock is moving while the gas ahead the
