Experimental Studies of Hypersonic Shock Impingement on a Transpiration-Cooled Flat Plate

Abstract

Hypersonic vehicle design requires mitigation of the high heat fluxes present in regions of shock-wave/boundary-layer interactions. A candidate technology that may be applied locally to these regions is transpiration cooling. In this work, experiments were conducted in the University of Oxford’s high-density tunnel at Mach 6.1 in both laminar and turbulent undisturbed boundary-layer regimes where a 10 deg shock generator impinged a strong oblique shock wave onto a transpiration-cooled microporous injector. For the laminar boundary layer, due to the strength of the incident shock, a transitional shock-wave/boundary-layer interaction region was formed with peak heating over 50 times greater than the nominal laminar level. Both nitrogen and helium were used as coolants. Relatively low levels of helium injection of for the transitional and for the turbulent scenarios were sufficient to reduce the heat transfer downstream of shock interaction to approximately 50% of the value without cooling. In fact, helium is highly effective with a similar cooling performance achieved as eight times the equivalent mass flux of nitrogen. The experimental data are correlated, and both the turbulent and transitional shock-impingement scenarios display a similar trend of reduced surface heat transfer with higher blowing parameters. Empirical fits are proposed that may be used for initial systems design.