柱形汇聚激波冲击球形重气体界面的实验研究

采用高速纹影法实验研究了柱形汇聚激波与球形重气体界面相互作用的 Richtmyer-Meshkov不稳定性问题. 激波管实验段基于激波动力学理论设计, 将马赫数为1.2 的平面激波转化为柱形汇聚激波, 气体界面由肥皂膜分隔六氟化硫(内)和空气(外)得到. 采用高速摄影机在单次实验中拍摄激波运动的全过程, 对柱形激波的形成进行了实验验证, 并进一步观测了汇聚激波与球形气体界面相互作用过程中的波系发展和气体界面变形以及反射激波同已变形界面二次作用的流场演化. 结果表明: 当柱形汇聚激波穿过气泡界面以后, 气泡左侧界面极点沿激波传播方向保持匀速运动, 气泡右侧界面发展成为射流结构, 气泡主体发展成为涡环结构; 在反射激波的二次作用下, 流场中无序运动显著增强并很快进入湍流混合阶段.

EXPERIMENTAL INVESTIGATION ON A SPHERICAL HEAVY-GAS INTERFACE ACCELERATED BY A CYLINDRICAL CONVERGING SHOCK WAVE

The Richtmyer-Meshkov instability of the interaction between a cylindrical converging shock wave and a spherical heavy-gas interface is studied experimentally using the high-speed schlieren photography.The shock tube test section is well-designed based on the shock dynamics theory,which can convert a planar incident shock wave with Mach number of 1.2 into a cylindrical converging shock wave.The spherical gas interface is formed by filling a soap bubble with sulfur hexafluoride（SF₆） surrounded by air.The high-speed video camera is used to record the complete process of the shock movement,which validates the method for generating cylindrical shock waves.The evolution of the wave propagation and the interface deformation after the passage of the cylindrical converging shock and the reshock is obtained during a single run.The results indicate that after the cylindrical shock passes across the bubble,the left interface of the bubble moves at a nearly constant velocity;the right interface of the bubble forms a jet and the main body of the bubble develops into a vortex ring. Subsequently,with the reshock impacting with the evolving interface,the disordered motion of the interface is intensified and the flow field quickly turns into a turbulent mixing.