Experimental Study on the Membraneless Heavy Gas Cylinder and Gas Curtain Interfaces Impacted by a Weak Shock Wave

A modified shock tube apparatus has been developed in order to experimentally investigate the evolution process of a sulfur hexafluoride gas cylinder and gas curtain surrounded by air when impacted by a shock wave with a Mach number of 1.2. By designing the test section, the fog generator, the gas chamber, the suction system and the end section, and controlling the sulfur hexafluoride peak concentration in the mixing gas and the initial vertical flow velocity, we developed a steady and repeatable technique to generate gas cylinder and gas curtain interfaces. Using high-speed camera, the initial interface images in the horizontal plane are obtained, and the developing photographs of dynamic Richtmyer-Meshkov (RM) instability in the vertical direction are also recorded. The gas cylinder evolution photographs exhibit typical vortex pair structure, and the gas curtain evolution images show multi-mushroom structure in the early stage and interfering with neighboring wavelength in the later stage. The height and width of the gas cylinder and the width of the gas curtain increase monotonically with time. Moreover the width increases faster than the height. The evolution mechanism of vortex is explained preliminarily, using two-dimensional vorticity dynamic equation.