Direct numerical simulation of incident shock–turbulent boundary layer interaction with chemical reactions

This study employs direct numerical simulations to explore the interaction between an oblique shock wave and a turbulent boundary layer under high-enthalpy conditions, accounting for chemical nonequilibrium effects. The investigation is conducted at a freestream Mach number of 10, where a shock wave inclined at 17 ∘ impinges on a turbulent boundary layer over a flat plate, causing flow separation and reattachment. The impact of chemical reactions is examined by comparing reactive and nonreactive flow conditions, using a five-species air model. The chemical reactions lead to a reduction in the mean flow temperature, which in turn causes an earlier transition to turbulence. In the shock-boundary layer interaction region, the reactive case exhibits a smaller separation bubble with a slightly higher dominant oscillation frequency, due to increased near-wall fluid momentum resulting from lower wall temperatures. Additionally, analysis of product mass fractions and Damköhler numbers highlights the presence of pronounced chemical nonequilibrium effects, particularly inside the separation bubble. Finally, it is found that turbulence has some effect in promoting the progress of chemical reactions toward equilibrium. Nevertheless, strong nonequilibrium states persist throughout the entire turbulent boundary layer.