Effects of corner rounding on aerothermodynamic properties in rarefied hypersonic flows over an open cavity

Abstract

A direct simulation Monte Carlo (DSMC) method is utilized to numerically investigate rarefied hypersonic flows over a group of two-dimensional rectangular cavities with rounded separation/reattachment corner. The effects of the rounded separation/reattachment corner on flow characteristics are discussed. The sensitivities of aerodynamic surface quantities are hence assessed comprehensively. Flows over the cavity configurations specified in the study hold the “open-cavity” characteristics and do not show any unsteadiness. The rounded separation corner does not significantly alter the flow patterns, while the rounded reattachment corner has a remarkable effect. Rounding the separation and reattachment corners can weaken the baroclinic effect in the separation and reattachment regions, respectively. For the rounded separation corner, it is easier for external gas molecules to enter the cavity and hence promote the momentum and energy exchanges with gas molecules inside the cavity. The fluid density inside the cavity, peak density at the reattachment point, pressure on and heat fluxes to the cavity floor are augmented, compared to those in the rectangular cavity case. However, the rounded reattachment corner may enhance the escape of gas molecules from the cavity and weaken the exchanges of momentum and energy. This leads to a significant decrease in the gas density inside the cavity, peak gas density at the reattachment point, pressure on and heat fluxes to the cavity floor. It is concluded that the approach of rounding the reattachment corner can achieve the most dramatic drop in the peak pressure and heat flux at the reattachment point. The research is guidable to the aerodynamic design of local configuration of hypersonic vehicles.