Compressibility effects in turbulent shear layers

For a number of reasons, it would be desirable to have a better understanding of the behavior of compressible turbulent shear layers. Such shear layers are important in the production of jet and rocket engine noise. They are present in supersonic combustion jet engine designs. Compressible shear layers are also important in many high power laser systems. In the present investigation, it is proposed to employ a Mach number M+ which may be of value in correlating compressibility effects. Experimental results showing the decrease of shear layer width with increasing Mach number are compared with the corresponding variations of theoretical instability growth rates calculated by Blumen et al. (1975). The agreement between theoretical and experimental results suggests that an important factor contributing to the decrease in the shear layer growth rate with increasing M+ is the decrease in the maximum growth rates of the large-scale Kelvin-Helmholtz instabilities.