二维凹面腔内连续超声速射流入射压力对激波聚焦的影响 *

Effectsof Continuous Supersonic Jet Pressureon Shock Focusin Two-Dimensional ConcaveCavity

关键词:  连续超声速射流  激波聚焦  入射压力  纹影  动态压力

Key words:  Continuous supersonic jet  Shock focus  Jet pressure  Schlieren  Dynamic pressure

摘要:

为研究射流入射压力对连续超声速射流对撞诱导激波聚焦的影响，开展了二维凹面腔内连续超声速射流对撞诱导激波聚焦的实验，分析了流场演化过程及动态压力特性。结果表明:连续超声速射流在凹面腔内对撞后出现了水平拉锯脉动模态和上下交叉脉动模态，在水平拉锯脉动模态中能实现频率为 9kHz左右的激波聚焦，实质是凹面腔内的气流周期性排出后形成的低压区导致射流喷管出口形成前导激波并在凹面腔底部聚焦；射流入射压力越小，凹面腔底部和射流对撞位置的压力脉动幅值越小，凹面腔底部激波聚焦的频率和强度越小，当入射压力减小到 0.3MPa后，凹面腔内无法实现激波聚焦。

Abstract:

In order to research the effects of continuous supersonic jet pressure on the shock focus，experi.ment of shock focus induced by continuous supersonic jet collision in two-dimensional concave cavity was carriedout and the changes of flow field and characteristics of dynamic pressure were analyzed. The results show that hor.izontal seesaw pulsation modal and up-down cross pulsation modal appear after continuous supersonic jet colli.sion in two-dimensional concave cavity，and shock focus with the frequency of about 9kHz can appear in horizon. tal seesaw pulsation modal，the substance is that the leading shock waves，which are induced at the jet nozzle out. let when flow exhaust from the concave cavity，focus at the bottom of the concave cavity. The pulsation amplitudeof pressure at the bottom of the concave cavity and the jet collision area and the strength and frequency of shockfocus at the bottom of the concave cavity decrease as the jet pressure decreases，shock focus can not appear in the concave cavity when the jet pressure decreases to 0.3MPa.