Numerical studies of real-gas effects on two-dimensional hypersonic shock-wave/boundary-layer interaction

Abstract

Nonequilibrium real-gas effects on surface heating rates, skin friction, and flow field unsteadiness of two-dimensional hypersonic shock-wave/boundary-layer interaction were studied by numerical simulations. The unsteady Navier–Stokes equations with nonequilibrium vibrational and chemical models for five-species air were solved by a finite-volume second-order TVD scheme together with a third-order semi-implicit Runge–Kutta scheme. Two cases of high-enthalpy shock/boundary layer interaction problems were studied in this paper. The freestream enthalpy was high enough to produce vibrational excitation and dissociation/recombination chemistry behind the shock. The first case was a steady two-dimensional shock/boundary layer interaction on a flat plate with a mixture of N2 and O2 in the freestream. It was found that the real gas effects reduce the size of the shock induced separation bubble and the magnitude of the surface heating rates. The second case was a self-sustained unsteady type IV shock–shock interference heating of a pure N2 flow over a cylinder. The results showed that type IV shock–shock interference heating flows with real-gas effects are inherently unsteady. Vortices are generated and shed off near the jet impingement point. This periodic shedding of the vortices contributes to the self-sustained oscillations of both the jet and other parts of the flow fields. In addition, the real-gas effects reduce the level of peak surface heating and peak surface pressure due to endothermic real-gas effects.