Flow Visualization in Compressible Turbulent Shear Layers.

Abstract

Cross-section Rayleigh scatter images have been obtained from a two-dimensional, compressible turbulent shear layer with isentropic convective Mach number M (i) c1 ranging from 0.09 to 0.92. With both streams beeing subsonic, the same two-dimensional large-scale Brown-Roshko structures have been found as in the Schlieren pictures from earlier experiments conducted in the same facility. These structures disappear from the Schlieren pictures when the high speed stream becomes supersonic, but for low M sup (i) c1 they are still visible in the Rayleigh scatter images. At higher compressibility levels the interface between the stream becomes very irregular in the Rayleigh scatter images. No strong shocks have been found inside the shear layer.