MULTIPLE NORMAL SHOCK-WAVE TURBULENT BOUNDARY-LAYER INTERACTIONS

A multiple normal shock/turbulent boundary-layer interaction in a rectangular duct has been investigated experimentally using a two-component laser Doppler velocimeter (LDV). Just upstream of the normal shock system the Mach number was 1.61, the unit Reynolds number was 30 x 10(6) m-1, and the confinement level as characterized by the ratio of the boundary-layer thickness to the duct half height was 0.32. The results presented here identify the fluid dynamic mechanisms involved in the reacceleration process following each shock in the multiple shock system. Two distinct expansion processes occur following each shock in the system: acceleration through a supersonic expansion fan originating near the wall and acceleration through an aerodynamic converging-diverging nozzle in the core flow.