EXPERIMENTALLY STUDY OF THE RICHTMYER-MESHKOV INSTABILITY AT N₂/SF₆ FLAT INTERFACES BY DIFFRACTED INCIDENT SHOCK WAVES AND RESHOCK

The developments of Richtmyer-Meshkov instability at gas interface subjected to a diffracted incident shock wave of low Mach number and reshock wave have been experimentally studied using the high-speed schlieren photography. The planar shock wave diffracted over a cylindrical column produces local perturbation at the gas interface. It has been demonstrated that the thickness of the interface grows slowly under the incident shock wave, while spike and bubble are clearly observed upon reshock. Moreover, the interaction between the reshock wave and the boundary layer generates wall vortices, which accelerates the development of turbulence mixing zone (TMZ). The post-reshock growth rate of TMZ is almost independent of pre-reshock conditions and in good agreement with the prediction of Mikaelian model. The reflected rarefaction wave from wall-end also accelerates the development of TMZ.