Cavitation intensity and erosion pattern of a self-excited cavitating jet

The self-excited water jet technology is widely used in submerged conditions, while its performance is restricted under high confining pressure. To improve its erosive capability, the cavitation intensity and the erosion pattern of a self-excited cavitating jet (SECJ) were investigated through mass loss and the microscopic images of the eroded specimens. The experiment was carried out in a certain range of cavitation numbers (σ = 0.05 ∼ 0.15), within which the SECJ can achieve strong oscillation. The results showed that, the cavitation intensity peaked at two optimum standoff distances under different cavitation numbers. The first one barely changed, while the second one decreased monotonously with increasing cavitation numbers. The selection of the optimum standoff distance was investigated for the jet to perform better erosion effect. Three typical erosion patterns containing several erosion rings were distinguished, of which different characteristics such as large erosion area or deep erosion valley could be achieved by adjusting the standoff distance. The variation of the erosion patterns under different conditions was preliminarily explained using an impingement model. The obtained results demonstrated that the SECJ could produce strong erosion under high confining pressure, and be effectively applied for material removal with low power consumption in submerged fields like deep-sea mining or ship hull cleaning.