INVESTIGATION ON ONSET OF SHOCK-INDUCED SEPARATION

A great number of experimental data indicating shock wave/boundary lay er interactions in internal or external supersonic flows were reviewed to make clear the mechanism of the interaction and to decide the onse t of shock-induced separation. The interesting conclusions were obtain ed for the considerably wide range of flow geometries that the onset o f separation is independent of the flow geometries and the boundary la yer Reynolds number. It is found that the pressure rise necessary to s eparate the boundary layer in supersonic external flows could be appli ed to such internal flows as overexpanded nozzles or diffusers. This i s due to the fact that the separation phenomenon caused by shock wave/ boundary layer interactions is processed through a supersonic decelera tion. The shock-induced separation in almost all of interacting flow f ields is governed by the concept of free interaction, and the onset of shock-induced separation is only a function of the Mach number just u pstream of shock wave. However, physical scales of the produced separa tion are not independent of the downstream flow fields.