Mean and turbulent velocity measurements of supersonic mixing layers |
| |
| Authors: | S G Goebel J C Dutton H Krier J P Renie |
| |
| Institution: | (1) Dept. of Mechanical and Industrial Engineering, University of Illinois at Urbana-Champaign, 61801 Urbana, IL, USA |
| |
| Abstract: | The behavior of supersonic mixing layers under three conditions has been examined by schlieren photography and laser Doppler velocimetry. In the schlieren photographs, some largescale, repetitive patterns were observed within the mixing layer; however, these structures do not appear to dominate the mixing layer character under the present flow conditions. It was found that higher levels of secondary freestream turbulence did not increase the peak turbulence intensity observed within the mixing layer, but slightly increased the growth rate. Higher levels of freestream turbulence also reduced the axial distance required for development of the mean velocity. At higher convective Mach numbers, the mixing layer growth rate was found to be smaller than that of an incompressible mixing layer at the same velocity and freestream density ratio. The increase in convective Mach number also caused a decrease in the turbulence intensity (
u
/ U).List of Symbols
a
speed of sound
-
b
total mixing layer thickness betweenU
1 – 0.1U andU
2 + 0.1U
-
f
normalized third moment ofu-velocity,f   u
3 /(U)3
-
g
normalized triple product ofu
2
v,g u
2
v/(U)3
-
h
normalized triple product ofu v
2, h uv'
2/(U)3
-
l
u
axial distance for similarity in the mean velocity
-
l
u
axial distance for similarity in the turbulence intensity
-
M
Mach number
-
M
c
convective Mach number (for  1=2),M
c
(U
1–U
2)/(a
1+a
2)
-
P
static pressure
-
r
freestream velocity ratio,rU
2/U
1
-
Re
unit Reynolds number,Re  U/
-
s
freestream density ratio,s
2/
1
-
T
t
total temperature
-
u
instantaneous streamwise velocity
-
u
deviation ofu-velocity,u u–U
-
U
local mean streamwise velocity
-
U
1
primary freestream velocity
-
U
2
secondary freestream velocity
-
U
average of freestream velocities, ¯U (U
1 +U
2)/2
-
U
freestream velocity difference,U U
1 –U
2
-
v
instantaneous transverse velocity
-
v
deviation ofv-velocity,v v – V
-
V
local mean transverse velocity
-
x
streamwise coordinate
-
y
transverse coordinate
-
y
0
transverse location of the mixing layer centerline
-
ensemble average
-
ratio of specific heats
-
boundary layer thickness (y-location at 99.5% of free-stream velocity)
-
similarity coordinate, (y –y
0)/b
-
compressible boundary layer momentum thickness
-
viscosity
-
density
-
standard deviation
-
dimensionless velocity,  (U –U
2)/U
- 1
primary stream
- 2
secondary stream
A version of this paper was presented at the 11th Symposium on Turbulence, October 17–19, 1988, University of Missouri-Rolla |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
