GALCIT Colloquium

Typically, a shock tube generates a shock wave with a high-pressure driver section that is separated from the low pressure driven section by a physical membrane. The membrane is burst at a specific pressure and a shock wave is formed. Using this type of apparatus, experiments are performed at Los Alamos National Laboratory to study the effect of incident shock Mach number (M) and initial conditions on the development of the Richtmyer-Meshkov instability after a shock wave impulsively accelerates a varicose-perturbed, heavy-gas curtain (air-SF6-air). The resulting instability and subsequent fluid mixing is measured using simultaneous Planar Laser-Induced Fluorescence (PLIF) and Particle Image Velocimetry (PIV). We investigate the mechanisms that drive the instability, at both large and small scales, by examining the time evolution of simultaneous, 2-D density (see figure) and vorticity fields for each Mach number and initial condition configuration. However, this process limits the repetition rate of experiments, and membrane particles must be removed from the shock tube after each experiment. Thus, we have developed a novel driver to generate shock waves in shock tube experiments. This driver does not contain a membrane. Instead, it uses a series of high-pressure chambers and fast-acting pistons to create the pressure jump between the high-pressure driver section and low pressure driven section. The entire system is controlled remotely and requires no insertion or cleanup of membranes fragments between experiments. It will allow high repetition rates, even in challenging experimental environments (such as the a vertical shock tube).