Joint experiments of cavitation jet: High-speed visualization and erosion test

Abstract

Cavitation is a ubiquitous phenomenon in ocean engineering. In order to figure out the relationship between cavitation cloud and cavitation erosion, high-speed visualization and erosion test of cavitation jet were simultaneously performed. The temporal and spatial distributions of cavitation cloud was analyzed using Proper Orthogonal Decomposition (POD) and the morphology of eroded specimen was analyzed from both macroscopic and microcosmic perspectives. The results show that POD modes of side view images are able to estimate the maximum radial distribution of cavitation pits, while the energy fraction of the first POD mode can serve as an indicator of specimen mass loss. The intensity of cavitation erosion is decided by both the bubble concentration and collapse intensity at specimen surface. At a medium standoff distance, where collapse intensity and bubble concentration are well compromised, maximum cavitation erosion is achieved. The aggravation of cavitation erosion is the combined consequences of the growth of single cavitation pits and the connection of adjacent pits. These results suggest that the collapse of cavitation bubbles is a necessary, but not sufficient, condition for severe cavitation erosion. The findings are expected to improve the physical understanding of the relationship between cavitation phenomenon and cavitation damage.