Sidewall influence of varying free stream Mach number in ramp induced shock wave boundary layer interactions

This study investigates the 3D effects introduced by the end walls for an aspect ratio 1 in ramp-induced shock wave boundary layer interactions. The simulations are performed using symmetry boundary condition in spanwise at free-stream Mach numbers in three dimensions. The simulations are done using an in-house compressible supersonic solver "OpenSBLIFVM"[1]. Two free stream Mach numbers 2.5, and 3 are utilised in the current work, the simulated results are compared with the aspect ratio 1 simulations of Mangalagiri and Jammy [2]. The inflow is initialized with a similarity solution; its Reynolds number based on the boundary layer thickness is adjusted such that the Reynolds number at the starting of the ramp is kept at 3×105 for all simulations. From the results, it is evident that the introduction of sidewalls resulted in a shorter centerline separation length when compared with the 2D simulations. This is contradictory to the results at Mach 2 by [2]. The vortex observed at Mach 2 by Mangalagiri and Jammy [2], in the central separation region, has vanished with increasing the free-stream Mach number. Also, the topology of interaction has changed from owl-like separation of the second kind to the first kind when the freestream Mach number has increased from 2 to 2.5. It can be concluded that, the topology of interaction is key to the increase or decrease of the central separation length when compared to 2D.