Numerical Investigation of Confinement Effect on Supersonic Turbulent Flow Past Backward Facing Step With And Without Transverse Injection

Abstract

Effect of confinement has been investigated numerically for supersonic turbulent flow past backward facing step in a nonreacting scramjet combustor. Flow structure downstream of the backward facing step has been studied by considering various configurations with different combustor heights as well as unconfined flow. Staged transverse sonic injectors with different combustor heights are also considered to find out the effect of confinement on the penetration, spreading and other flow features in the flow field. Three dimensional Navier Stokes equations along with k-ε turbulence model are solved using a commercial CFD software. The simulation captures all essential features of the flow. Good comparisons of various flow profiles have been obtained between experimental and computed values. Although confinement creates complicated shock reflections in the combustor, the length of the recirculation bubble behind the backward facing step remains almost constant. For the injection case, the recirculation region is extended upto the bow shock arising upstream of the injector and two recirculation bubble is seen between the backward facing step and the injector.