Investigation of the Richtmyer-Meshkov instability with double perturbation interface in nonuniform flows.

A nonuniform SF6 gas flow initial condition has been actualized in the context of shock tube experiment for the Richtmyer-Meshkov instability study. Two kinds of amplitude have been used to design the membrane supports which initially materialize the gaseous interface. The visualizations of air/SF6 sinusoidal interfaces and shock wave propagations in the nonuniform field were obtained by Schlieren photography. Experiments are in very good agreement with simulations for the air/SF6 case, but due to the initial nonuniform effects, Sadot model and Zhang-Sohn theory are far beyond the experimental and calculation results.

Experimental and numerical study of shock-accelerated elliptic heavy gas cylinders.

We studied the evolution of elliptic heavy SF6 gas cylinder surrounded by air when accelerated by a planar Mach 1.25 shock. A multiple dynamics imaging technology has been used to obtain one image of the experimental initial conditions and five images of the time evolution of elliptic cylinder. We compared the width and height of the circular and two kinds of elliptic gas cylinders and analyzed the vortex strength of the elliptic ones. Simulations are in very good agreement with the experiments, but due to the different initial gas cylinder shapes, a certain difference of the initial density peak and distribution exists between the circular and elliptic gas cylinders, and the latter initial state is more sensitive and more inenarrable.