Page 200 - 48Fundamentals of Compressible Fluid Mechanics

162 CHAPTER 9. FANNO FLOW
P2/P1 Fanno Flow

4fL
¾¾
D
4.8
4.4
4
3.6
5 %
3.2
50 %
2.8 75 %
P2/P1 2.4

2
1.6
1.2
0.8
0.4
0
0 0.05 0.1 0.15 0.2 0.25
4fL
¾¾
D
Fri Nov 12 04:07:34 2004

Fig. 9.14: Fanno Flow Mach number as a function of when the total

9.7.3 Entrance Mach number, , effects

In this discussion, the effect of changing the throat area on the nozzle efficiency are
neglected. In reality these effects have significance and needed to be accounted
for in some instances. This dissection deals only when the flow reaches the su-
personic branch reached otherwise the flow is subsonic with regular effects.. It is
is large enough to create

assumed that in this discussion that the pressure ratio
is small enough to allow it to happen.
is a function of the ratio of the nozzle’s
a choked flow and W`XaZ [
throat area to the nozzle exit area and its efficiency. This effect is the third parame-
b
The entrance Mach number, N
ter discussed here. Practically, the nozzle area ratio change by changing the throat
area.
; first is
of the supper sonic which deponent only the specific heat,
As was shown before, there are two different maximums for WYXaZ [
. This
the total maximum W`XaZ [
b
F , and second the maximum depends on the entrance Mach number, N