The interaction between a sonic jet and an oblique shock wave in a supersonic crossflow

The current study considers the configuration of a transverse jet in a supersonic crossflow that is interacting with an impinging oblique shock wave. The relevance of this configuration is associated to high-speed air-breathing propulsion systems, where a shock may be induced in the combustion chamber to enhance mixing. To investigate the behaviour of this system, experiments were conducted in a supersonic test facility at a freestream Mach number of 2, analyzing the effect of three main control variables: the jet momentum flux ratio, the shock strength and the impingement position of the shock on the jet plume. Measurements were acquired using surface oil-flow visualization, schlieren photography and Particle Image Velocimetry. Results reveal that near-field momentum-driven mixing remains largely unaffected after the introduction of the impinging shock wave, while mid-to-far-field mixing mechanisms do change. An increase in jet plume elevation was observed, as well as the formation of a strong shear layer downstream of the jet, which acts as a source of vorticity that promotes entrainment towards the jet mid-field. A stronger shock wave was found to be more beneficial for mixing performance. This effect was seen to decrease with weakening shock strength or by shifting the strong shock further downstream.