Shock-wave/shear layer interaction in circular supersonic jets

The interaction between shock-waves and large coherent structures in a turbulent compressible jet flow, is studied experimentally. The results are compared qualitatively with trends predicted by the linear stability theory. The techniques developed for analyzing the stability of circular jets are extended to include the shock-cell interaction with the instability waves. The controlling effect on the shear layer evolution, of the turbulent initial conditions, the shape of initial mean velocity profile, and Reynolds and Mach numbers are investigated. The shock wave strength is varied as well as the shear layer parameters, i.e., mean and turbulent velocity distribution, thickness, etc. These parameters determine the extent of penetration of the shock into the shear layer, the compression/expansion pattern, the diffusion rate of the shocks, and the shear layer instability characteristics. A possible feedback which is generated by the sound emitted from the shock/vortices interaction locations and subsequently excites the roll-up of vortices in the shear-layer, is discussed