Dynamics of quasi-empty rupture in the layer of cavitating liquid under SW-loading

Abstract

The problem of formation and collapse of a quasi-empty rupture in the layer of a cavitating liquid under shock wave (SW) loading is considered. The SW-pulse is generated in the layer by electro-magnetic hydrodynamic shock tube in a result of high-voltage discharge of capacitor bank on a flat helical coil. The latter is located right up to the bottom (conducting membrane) of container with the layer of two-phase distilled liquid. The analysis of the experimental data shows that the rupture is shaped as a spherical segment, which retains its topology during the entire process of its evolution and collapse. It was shown that potential energy of maximum volume of rupture at its collapse is practically transformed in acoustical losses (SW-radiation) and rupture disappears. Dynamics of main parameters and an existence time of rupture were determined. The analysis of cavitating nuclei state in the form of thin layer on an entire interface of rupture shows that in the field of rupture collapse the thin cavitating layer is transformed to a cavitating cluster. The latter takes the form of a ring-shaped bubbly vortex floating upward to the free surface of the liquid layer. A р-к two-phase mathematical model was formulated, and calculations were performed to investigate the collapse of a quasi-empty spherical cavity (rupture model) in the unbounded cavitating liquid, generation of ultra-short shock wave and to discover the dynamic growth of micro-bubbles in a cluster by five orders of magnitude. [Work supported by RFBR Grant 15-05-03336.]