Experiments on the Richtmyer-Meshkov Instability in a dual-shock vertical shock tube

Experiments on the Richtmyer-Meshkov Instability (RMI) using Particle Image Velocimetry (PIV) in a dual-shock vertical shock tube are presented. Two shock waves travel in opposing directions impact an initially stably stratified, perturbed interface formed between Air and Sulfur Hexaflouride (SF₆). Perturbations are formed using a pair of voice coil driven pistons that generate Faraday waves on the interface. The incident shock wave arrives from air side of the interface which initiates the RMI. Shortly afterward a second shock wave arrives from the SF₆ side which generates reshock. The temporal separation between the arrival of the two shock waves is controlled so that the effect of varying the shock-to-reshock time period may be studied. Shock strengths are chosen to result in halted interface motion after passage of the second shock wave, permitting a long observational window in which the instability can evolve and yielding a simplified optical and recording setup as compared to typical single-driver experiments. Information on the growth of the RMI, including measurements of the growth exponent, θ, as measured both from the decay of turbulent kinetic energy and the growth of the mixing layer enstrophy width, is presented.