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A special designed supersonic wind tunnel with twin nozzle and
single test section has been used to investigated the
characteristics of two-dimensional supersonic mixing shear
layer by using the laser holographic interferometry technique.
The centerbody coutours of the twin nozzle models is a
combination of a segment of rectangular symmetric supersonic
nozzle coutour, which was designed by the method of
characteristics, and a segment of splitter plate, which was
designed to produce uniform flows on each side of the twin
nozzle. Four mixing layer cases were examined, with convection
Mach numbers below 0.25. The flow visulaization pictures and
the Mach number, pressure and density distributions with the
infinite fringe analysis have been obtained. It shows that
there is no large scale vortical structure in shear layer.
With the two supersonic streams of different pressure, the
mixing layer has a angle of inclination. Near the trailing
edge of splitter plate, expansion waves and compression waves
are formed. Due to the incline angle and the effect of finite
thickness of splitter plate. The shear layer thickness grows
linearly to the downstream as shown on the pictures except in
the near wake portions where the layers are not fully
developed. Comparing the results obtained by using the
convection Mach number concept along with a technique to
predict compressible free shear layer growth rates， both of
the results is comparable.
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