Study on two-dimensional and three-dimensional secondary jet interactions with a supersonic flow

Shock wave/turbulent boundary layer interaction regions induced by gaseous secondary flows injected into supersonic flows through slot and circular nozzles have been investigated. Experiments are conducted at freestream Mach number of 3.75 to approximately 3.81, total pressure of 1.20 MPa, total temperature, T₀, of 283 to approximately 299 K and Reynolds numbers based on the distance between the leading edge of the flat plate and the nozzle exit of 1.03 to approximately 2.07×10⁷ under the almost adiabatic wall condition. In the experiments the flow fields are visualized by the Schlieren method, oil flow technique and surface pressure distributions are measured in the whole interaction region. The total pressure ratio, P_c/P₀, (P_c: total pressure of injected secondary flow, P₀: total pressure of freestream) and the width of the slot are varied and the change of the flow field are investigated. The results show that the bow shock wave/turbulent boundary layer interaction induces the boundary layer separation in front of the injection. In the interacting flow, barrel shock waves and Mach disk are observed clearly. As the total pressure ratio or thickness of nozzle is increased, the separation region, the extent of the interaction region and shock structures become large significantly. Also the remarkable difference of the flow structure between slotted injection and circular injection has been revealed.