Experimental and numerical investigation of vortex dynamics in ventilated cavitating flows around a bluff body

摘要

The objective of this paper is to investigate ventilated cavitating vortex shedding dynamics around a bluff body at Re=6.7×10~4 by experimental and numerical methods. The couple level-set and VOF (CLSVOF) method is applied to capture the air-water interface. The results show that the CLSVOF method can predict the air-water interface accurately. Two types of unsteady ventilated cavitating flows are investigated, namely vortex shedding structure (Q_v=0.174) and the Re-entrant jet (Q_v=0.31). The finite-time Lyapunov exponent (FTLE) and Lagrangian coherent structures (LCS) methods are applied to investigate the formation, evolution and shedding of ventilated cavitating vortices. For vortex shedding structure (Q_v=0.174), the vortices alternately shed from the cavity, forming the vortex street. For the re-entrant jet structures (Q_v=0.31), there exist the interaction between the vortex shedding and the re-entrant jet. The evolution of ventilated cavitation is divided into three stages: the vortex shedding, the development of re-entrant jet and the development of ventilated cavitation.