Cavitation cloud evolution and erosion by cavitation water jets applied to curved surfaces

Cavitation water jets produce clouds of cavitation bubbles that erode surfaces and are therefore widely used in numerous applications. Previous studies have focused on evaluating cavitation characteristics by jetting water over a plane surface. However, in practical applications, the surfaces of many housings or components are curved. Curved surface constraints have an effect on the fundamental properties and impact performance of cavitation clouds. This study used high-speed photography to observe the evolution of cavitation clouds and their associated ring vortexs as they interacted with both curved and planar surfaces. The frequency and spatial structure distributions of the cavitation clouds were analysed by proper orthogonal decomposition (POD). Following this, erosion experiments were conducted and the surface morphology observed using scanning electron microscopy. The experimental results show that when constrained by a curved surface, the cavitation cloud expands along the wall, leading to a decrease in the concentration of the cavitation cloud in the central region. In addition, POD analysis shows that the presence of two prominent cavitation shedding peaks greatly reduces the periodicity of cavitation cloud shedding evolution on curved surfaces. Vortex shedding is not prominent on the curved surface compared to the plane surface. The flow field reconstructed using the initial four models reveals the evolution of the large-scale structure. However, on the curved surfaces, the proportion of small-scale structures is much larger, making the reconstructed large-scale flow field difficult to predict. The erosion results show that the curved surface constraint effect results in significantly smaller mass loss on curved surfaces than on planar surfaces.