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.