Mach wave suppression using a pair of third helical modes with low phase velocity in a supersonic jet

Abstract

The three-dimensional compressible Navier-Stokes equations are numerically solved to study suppress Mach wave emission in a supersonic round jet at high Mach number using high-order compact upwind schemes. Two cases of inlet disturbance for Mach number M_j=2.0 are presented. The first case is the jet flow forced randomly. The second case is the jet forced by random disturbances and a pair of unstable helical modes (m=±3，m=±3) with a subsonic phase speed. The numerical results show that the jet potential core region is reduced in the jet forced by a pair of the helical modes with a subsonic phase speed. In the relatively high amplitude case, the helical modes with high frequency tends to have a high suppression effect of Mach wave.