A numerical analysis of boundary-layer/shock wave interactions in the compression ramps of scramjet intakes

As part of the studies, at the Aerothermodynamics and Hypersonics Division (EAH) of the Institute for Advanced Studies (IEAv), aimed at flight demonstration of a hypersonic vehicle prototype powered by a scramjet engine, a series of numerical simulations have been performed for the inlet of the present vehicle configuration (14-XB) of the 14-X hypersonic vehicle prototype. The aim was to analyze the development of the boundary-layer and its interaction with the shock wave from the compression ramp, which may cause flow separation. First, an analysis is performed on the boundary-layer development at the vehicle forebody, the thickness of which can be considerably large in these flow conditions. Second, a validation study of the transitional viscous flow models and numerical methods available was performed for the simple geometry of a flat plate attached to a compression ramp, compared with similar experimental results from the literature. Results show that the transitional flow models are quite accurate at simulating the flow separation. Finally, a detailed numerical study was performed for the inlet of the 14-XB vehicle, analysing both adiabatic and cold wall conditions, where separation is visible in both, albeit larger for the adiabatic cases. This is invaluable for the development of the engine as these separations alter the flow field in such a way that may lead to engine unstart or adverse conditions at the combustor