Interaction between underexpanded supersonic jet and obstacle

摘要

When an underexpanded supersonic jet impinges on an obstacle, a self-induced flow oscillation occurs. This oscillation depends on the pressure ratio in the flowfield, the position of an obstacle and is related to the noise problems of aeronautical and other industrial engineering. The characteristic and the mechanism of self-induced flow oscillation, therefore, have to be understood to control the various noise problems. The characteristics of the oscillatory flowfield and the mechanism of an oscillation have to be studied further to control the oscillation. This paper aims to clarify the effect of the pressure ratio and the obstacle position on the mechanism of self-induced flow oscillation by the numerical analysis and the experiment, when the underexpanded supersonic jet impinges on the cylindrical body. From the result of this study, it is clear that occurrence of self-induced flow oscillation depends on the pressure balance in the flowfield.