Flow Characteristics of Mixed Compression Inlet

Mixed compression inlets in ramjet engines serve to decelerate and compress the incoming flow, reducing it to subsonic speeds. This process ensures an appropriate mass flow rate into the engine. Experimental and numerical investigations were performed to characterize a mixed compression inlet. Experimental testing was carried out at Mach 3 while acquiring pressure measurements, Schlieren, and pressure sensitive paint. Pressure distributions over the model showcased the isentropic compression process and reflected shocks with strong spanwise uniformity. The numerical simulations were performed using implicit large eddy simulations (ILES) to capture the unsteady flow field. The numerical analysis highlights the development of the boundary layer on the external compression and inside the internal compression region. As the cowl shock impinges on the junction along ramp wall, the flow separates and leads to the generation of two distinct shock trains inside the isolator. These shock trains through reflections within the isolator, achieve internal compression. The reflection of the reattachment shock inside the isolator is more susceptible to unsteadiness than separation shock, which amplifies instabilities in the cowl SBLI region.