Page 143 - 48Fundamentals of Compressible Fluid Mechanics

In the previous two chapters, the flow in a variable area duct and the normal shock
(discontinuity) were discussed. A discussion of the occurrences of shock in flow
in a variable is presented. As is was presented before, the shock can occur only
when there is a supersonic flow. As it was shown in Chapter 5, the gas has to pass
trough a converging–diverging nozzle to obtain a supersonic flow. Thus, the study
of the normal shock in converging–diverging nozzle is presented.
In the previous Chap-
ter, the flow in a convergent–
divergent nuzzle was presented
when the pressure ratio was
above or below the special
range. In this Chapter, the flow
in this special range of pres-
sure ratios is presented. It is in-
c
teresting to note that a normal
a
shock must occur in these situ-
ations (pressure ratios). Subsonic
subsonic flow after
In figure (6.1) the re- a shock d
duced pressure distribution in Supersonic
b
the converging–diverging noz-
distance, x
zle is shown in whole range
pressure ratios. In case, when Fig. 6.1: The flow in the nozzle with different back pres-
B is be- sures
tween point “a” and point “b” the
the pressure ratio,
105