Aerothermodynamic characteristics of hypersonic curved compression ramp flows with bistable states

Abstract

The aerothermodynamic characteristics (including wall friction Cf, pressure pw, and heat flux St) in curved compression ramp (CCR) flows with bistable states are studied numerically and theoretically. Direct numerical simulations of bistable states of separation/attachment induced by variation of the turning angle ϕ, as well as the influence of inflow Mach number and wall temperature on dual-solution interval, are carried out. Distributions of wall friction, pressure and heat flux are analyzed. Further, the emergence of the first and second minima of Cf in the separation bubble is interpreted, which are dominated by the adverse pressure gradient induced by separation and reattachment shock, respectively. The present results and analysis indicate that the reversed-flow singularity of F. T. Smith (Proc. R. Soc. London. A: Math. Phys. Sci. 420, 21–52 (1988)] is less likely to occur in CCR flows. The prediction of pressure peak ppk of separation states confirms the model based on the minimum viscous dissipation theorem [Hu et al., Phys. Fluids 32(10), 101702 (2020)]. While the pressure overshoot pos can be analyzed by shock-polars with pressure match of compression and expansion process. The correlation between heat flux peak and pressure peak of both separation and attachment states is also discussed in terms of the classical power relation.