Hypersonic boundary-layer flow with an obstacle in thermochemical equilibrium and nonequilibrium

Abstract

The hypersonic flowaround a tip of a rocket-mounted Hypersonic Boundary-Layer Transition experiment has been simulated with direct numerical simulations. The numerical results reveal the local flow conditions at the location of a surface-mounted cuboid on the wedge-shaped geometry roughly 50 cm downstream of the leading edge for ideal-gas, chemical-equilibrium, and nonequilibrium conditions. The Ma∞ = 8.5 flow is subject to an oblique shock to deliver about Ma = 6.3 at the boundary-layer edge at the cuboid depending on the gasmodel used.The flowaround the object ofabout one-third of the boundary-layer thickness in height is influencedbythe chemicalmodeling of the air,andreveals differentwakes downstreamof the cuboid. The details of the flowdepending on the chemicalmodel employed underline the necessity for nonequilibriumsimulations under the conditions investigated.The laminarwake shows hot fluid being transported close to the surface through the trailing longitudinal vortices, increasing the heat flux at the wall for the chemically reacting cases, most notably for the nonequilibrium case, compared to an ideal-gas comparative case. Although the maximum temperature in the wake decreases for the chemically reacting flows, the location of the maximum moves closer to the wall amounting to a net increase in heat transfer.