关键词: 高超声速, 钝双楔, 转捩, 分离流动, 壁温

Abstract:

To study the effect of different wall temperatures on the engine inlet transition flow for an air breathing hypersonic vehicle, a typical model of blunt double wedge is chosen in this paper. Based on the tunnel experiments carried by Thomas and Herbert from Aachen University in Germany, some existing computational fluid dynamics (CFD) results are analyzed and compared with the numerical simulation results obtained by different methods in the paper. So the effect of different wall temperatures on the transition flow and separated flow in hypersonic flow around a double wedge is discussed. About the flow around the double wedge the separated flow generally occurs around the corner, and the stress of the separated vortex induces the transition, so the intensity and the size of separated flow change, finally the complicated interaction of non-stationary vortex movement and flow transition occurs. The calculation results show that the numerical simulations carried out considering transition simulation accord with the tunnel experiments. Also the comparing results between the calculation and the experiments show that in the literature, the results obtained by using laminar flow solver on the first ramp and turbulent flow solver on the second ramp are consistent with the experimental data, and in the paper the results obtained from the simulation only using the combined method of MUSCL, shear stress transport (SST) model and γ-Re_θ model accord with the experimental data and reproduce rightly the status of the tunnel experiment. The analysis shows that in the region before the separated flow the wall heat flux decreases and the viscosity coefficient near wall increases with the wall temperature increasing; in the boundary layer the velocity profile is not in full and the velocity boundary layer is thicker, so the separated flow occurs even easier.

Key words: hypersonic, blunt double wedge, transition, separated flow, wall temperature