Numerical simulation of cavitation bubble collapse within a droplet

Cavitation bubble always exists in the droplets breaking up from the fuel jet when supercavitation phenomenon occurs. The collapse of cavitation bubble plays an important role in secondary breakup of droplets. The collapse process of cavitation bubble within the diesel droplet considering the phase change or not have been simulated numerically based on the volume of fluid (VOF) method using OpenFOAM. The results show that collapse process without phase change consists of multiple collapse and rebound stages, similar to the vibration process of a damping spring oscillator. Considering the phase change, there is only collapse stage and no rebound stage in collapse process, and the variation of bubble volume with time is no longer cyclic. The collapse speed become faster with the increasing of environmental pressure, while the collapse speed become faster with the decreasing of saturation vapor pressure. The effect of surrounding pressure on collapse process is greater than the effect of saturation vapor pressure. (C) 2017 Elsevier Ltd. All rights reserved.