Investigation On Two-dimensional Shock Reflection Hysteresis In Steady Supersonic Flows

The shock reflection hysteresis phenomenon exists widely in the external flow field of aerospace craft and the inner flow field of power plant. Combining with the present research status at home and abroad, this article which pays more attentions to the configurations in different shock reflection patterns and the evolution during the hysteresis process, investigates two-dimensional steady shock reflection hysteresis phenomenon theoretically, numerically and experimentally.First of all, the inviscid studies on the configuration of two-dimensional steady shock reflection, the way to realize the transition between the two shock reflection patterns, and the evolution during the hysteresis process are conducted, theoretically,numerically and experimentally. In the research of theory, the region of dual solution domain is ascertained theoretically by using shock polar,the inviscid shock reflection wave configuration is described, and the hysteresis phenomenon is confirmed.Meanwhile, each situation of the hysteresis phenomenon which is induced by the flow Mach number variation or the wedge angle variation is discussed. In experimental study,the fine structures of shock reflection configuration are given experimentally for the first time, using Nano-tracer Planar Laser Scattering(NPLS) technique. Also, the evolution of slipstreams in different shock reflection patterns are discussed respectively.Similar to the evolution of supersonic mixing layer, the evolution of slipstream in Mach reflection pattern also can be divided into three stages: laminar, K-H vortex, vortex break up. In the numerical study, based on the theoretical analysis, a new way to achieve the shock reflection hysteresis is proposed numerically. By adding counter-flow at the leading edge of wedges, it is possible to realize the mutual transition between the regular reflection pattern and the Mach reflection pattern. Furthermore, by mean of further analysis on the shock angle at the reflection point and the Mach stem height during the hysteresis process, the reasons for bidirectional transition are given.Second, aiming at the shock reflection configurations when the boundary layer developed over the reflecting surface are taken into consideration, a great deal of research are conducted, theoretically, numerically and experimentally. In the research of theory, Combined the free-interaction theory with the shock reflection hysteresis theory,a detailed analysis describing the viscous flow structures of shock reflection configurations is proposed. After analysis, the shock reflection pattern in the viscous flow field may has two solutions, which is similar to the situation in inviscid studies.Furthermore, based on a hypothesis that the interaction origin keep invariable during the shock-boundary-layer interaction, the viscous shock reflection hysteresis which is similar to the one that exists in the reflection of symmetric shock waves is confirmedtheoretically. For verifying the theoretical results, this article obtains the viscous shock reflection configuration in different shock reflection pattern, by solving the Navier-Stokes equations. Also, the viscous hysteresis process which is induced by the flow Mach number variation is analyzed. After quantitative processing, the numerical results not only give the reasons for hysteresis, but also verify the accuracy of the theoretical model. Similarly, the experimental results not only show that the viscous shock reflection configurations exist in the real flow, but also verify the accuracy of the theoretical model.Finally, combined with the application background in supersonic inlet, this article try to describe the un-start flow field in the inlet under the over-rated condition, by using the above analysis method which is about the viscous shock reflection. The results show that the un-start flow field under over-rated condition differs from that under rated/ sub-rated condition. The shock generated by forebody incidence into the wall of inlet lip, and reflect many times into the burner. It may induce the boundary layer separates. According to the viscous model, the inlet viscous flow field may has two solutions, because of the hysteresis phenomenon. It also mean that two different viscous flow fields in the inlet can be obtained, under the same conditions. Concretely, the compression angle of the the separation zone and the separation shock angle in two flow fields are approximately close, in spite of the large difference in separation size and shape. As for the engineering problems, such as the performance between the two fields,the relation between the hysteresis and the inlet starting performance, they should be further expanded in the future work.