Experimental study on interacting flow fields induced by normally injected secondary flow through a slot nozzle into supersonic flow

The complex flowfields induced by gaseous secondary flow injected into supersonic flow have been studied experimentally. A gaseous nitrogen jet is injected normally into the external flow through a transverse slot nozzle mounted on the flat plate model. Experiments are conducted under the conditions of free stream Mach number of 3.8, total pressure of 1.2MPa, Reynolds number of 2.0×10⁷. In the flowfields, widths of slot nozzles and P_c/P₀ (P_c :total pressure of secondary flow, P₀ :total pressure of free stream) are used as primary parameters. 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.