反射激波作用重气柱的Richtmyer-Meshkov不稳定性的实验研究

Experimental study of Richtmyer-Meshkov instability in a heavy gas cylinder interacting with reflected shock wave

采用高速摄影结合激光片光源技术,研究了反射激波冲击空气环境中重气体(SF6)气柱的Richtmyer-Meshkov不稳定性。通过在横式激波管试验段采用可移动反射端壁获得不同反射距离,实现了反射激波在不同时刻二次冲击处于演化中后期的气柱界面,得到了不同的界面演化规律。反射距离较小时,斜压机制对气柱界面形态演化的影响显著,界面衍生出二次涡对结构;反射距离较大时,压力扰动机制的影响显著,界面在流向上被明显地压缩,没有形成明显的涡结构。由气柱界面形态的时间演化图像得到了界面位置和整体尺度随时间的变化,对反射激波作用后气柱界面的演化进行了量化分析。

The Richtmyer-Meshkov（RM）instability in a heavy gas（SF6）cylinder surrounded by ambient air is experimentally studied using a high-speed video camera in combination with a laser sheet.The evolving gas cylinder at intermediate to later stages was reshocked by the reflected shock wave at different times along with the changes of the endwall distance,which was achieved by designing a movable endwall for the test section in a horizontal shock tube.It is demonstrated that different endwall distances result in different evolutions of the reshocked interface.For a short endwall distance,the effect of the baroclinic mechanism on the interface evolution is significant and a secondary vortex pair is formed,while for a long endwall distance,the effect of the pressure perturbation mechanism is significant and the streamwise compression of the interface instead of vortex structure is clearly observable.In addition,quantitative analysis is conducted by measuring the position and the integral scale of the interface from sequences of images.