Suppression of embedded shocks in supersonic free-shear-layer structures

Although the suppressed instability of supersonic free shear layer flow has been documented by many investigators, the underlying physics are still ambiguous. In the present study, numerical simulations were performed to cast physical insight into the two-dimensional large-scale structure which is organized in a supersonic free shear layer. It is found that an acoustic interaction of the disturbed shear layer with a flow channel wall or another shear layer is indispensable to generate the organized structure. The undisturbed vorticity layer is deformed into a traveling wavy one. As the flow Mach number increases, its degree of deformation decreases so that the formation of shock waves embedded in the structure is avoided. Received 4 August 1995 / Accepted 6 March 1996