Page 150 - 48Fundamentals of Compressible Fluid Mechanics
P. 150
112 CHAPTER 6. NORMAL SHOCK IN VARIABLE DUCT AREAS
P 01
The efficiency of the diffuser is defined
h P 02
as the ratio of the enthalpy change that
P 2
occurred between the entrance to exit 0 1
0 2
stagnation pressure to the kinetic en-
2 P 1
ergy.
(6.6)
1
s,entropy
For perfect gas equation (??) can be
converted to Fig. 6.3: Description to clarify the definition of
diffuser efficiency
(6.7)
And further expanding equation (6.7) results in
(6.8)
%
%
#
% #
Example 6.3:
"
A wind tunnel combined from
a nozzle and a diffuser (actu- nozzle Diffuser
ally two nozzles connected by a 1
constant area see Figure (6.4)) 2 3 4
the required condition at point
and pres- capacitor
and tempera-
. The cross sec-
3 are:
tion in area between the nuzzle Compressor
ture of
. What is
area of nozzle’s throat and what cooler
sure of
)(
and diffuser is
is area of the diffuser’s throat to
maintain chocked diffuser with
subsonic flow in the expansion heat
section. can be as- out
sumed. Assume that a shock
occors in the test section.
Fig. 6.4: Schematic of a supersonic tunnel in a contin-
uous region (and also for example (6.3)
SOLUTION
The condition at
is summarized in following table
%
3'
3
(
!(/3
3 (