Direct numerical simulation of high enthalpy shock wave/turbulent boundary layer interaction

Shock wave/turbulent boundary layer interaction widely exists in the external flow of hypersonic aircraft. With the increase in the flight Mach number of new hypersonic aircraft，the gas may dissociate in the high-temperature environment after the leading shock，resulting in high enthalpy shock wave/turbulent boundary layer interaction. Compared with perfect gas，the chemical nonequilibrium effect in high enthalpy flow may have a strong coupling effect with turbulence and shock wave，further complicating the flying environment. However，related studies are limited. This study performed direct numerical simulation of high enthalpy shock wave/turbulent boundary layer interaction based on the flow condition after the leading shock of a cone in the hypersonic flight. Compared with the low enthalpy flow under similar conditions，the influence mechanism of high-temperature chemical nonequilibrium effect on flow separation and the influence of component diffusion are studied. The results show that the effects of high-temperature chemical nonequilibrium on Reynolds stress distribution and turbulent kinetic energy transport are not obvious. However，it has a significant impact on flow separation. The separation area of high enthalpy flow is much smaller than that at low enthalpy，possibly due to the increasing momentum of the upstream boundary layer and the increasing density of the separation bubble. Unsteady analysis reveals that the flow separation state under the high enthalpy condition is transient separation while average separation under the low enthalpy condition. The energy in the reverse area under both conditions is mainly low and middle frequency，although the low frequency energy under the low enthalpy condition accounts for a larger proportion. Furthermore，through the proper orthogonal decomposition of the streamwise velocity pulsation and oxygen atoms mass fraction pulsation in the high enthalpy interaction area，it is found that the energy during the separation bubble change mainly concentrates in the shear layer，consistent with the result of low enthalpy. The energy modes of the gas component are the highest at the separation shock wave，indicating that the shock wave is the main cause for the component pulsation. © 2023 AAAS Press of Chinese Society of Aeronautics and Astronautics. All rights reserved.