关键词: 激波串；激波振荡；风洞实验；动态特性

Abstract: The structure and dynamics characteristics of oblique shock train in a simple duct model are investigated experimentally in a Mach 5 hypersonic wind tunnel. Back pressure of model is produced and varied by the close of two ramps at the end of model. Measurements made include high-speed schlieren imaging and simultaneous fast-response wall pressure along the length of model. Results show that the leading edge of shock train propagates upstream,and translates to be asymmetry with the increase of back pressure. The asymmetry state maintained throughout the last whole propagation process. Varying the rise speed of back pressure did not show any discernible effects with regard to propagated speed of the leading edge of oblique shock train. There are two kinds of motion in the shock train propagation process: steadily forward and rapidly forward. The characters of shock train propagation are decided by the fluid structure,the pressure distribution of wall,the magnitude of back pressure,and the distance to the isolator exit,etc. Different wall pressure spectral characteristics of oblique shock train in duct are explored with different back pressure. But in the same case,all the pressure spectral characteristics of transducers in the shock train region are similar. In Case 1,the dominant frequency is f1=512Hz；in Case 2,the dominant frequency is f1=578Hz,the secondary frequency is f2=260Hz that is close to the acoustic resonance frequency. Both the dominant frequencies obtained in the experiments are higher than those of the theoretical prediction of Piponniau model.

Key words: Shock Train；Shock oscillation；Wind tunnel experiment；Dynamic Characteristics