Shock-Wave/Boundary-Layer Interactions in a Model Scramjet Intake

Abstract

An air intake for a Mach 8 flight vehicle concept has been studied using large-eddy simulation with flow conditions corresponding to typical wind-tunnel tests. The flow contains several types of shock-wave/boundary-layer interaction for which large-eddy simulation has advantages over conventional Reynolds-averaged Navier-Stokes approaches. Laminar-to-turbulent transition was triggered using localized blowing trips in the first external ramp surface close to the intake leading edge. The trips lead to turbulent spots that propagate within an otherwise laminar flow, with a lateral spreading angle consistent with previous studies. The transitional/turbulent shock interaction near the. first compression corner was found to enhance the transition to turbulence, leading to a fully turbulent boundary layer after the interaction. Further downstream, a large separation zone forms due to the cowl-lip shock wave impinging on the vehicle-side boundary layer. Perturbations from the vehicle-side turbulent boundary layer were found to enter the cowl-side boundary layer. The final transition of this boundary layer occurred at the end of a separation bubble created by the first cowl-side compression ramp. Statistics for the turbulent How entering the combustor inlet show thick nonequilibrium turbulent boundary layers and trapped compression waves.