Marked Effects of Ambient Pressure on Impinging Erosion Induced by High-Speed Submerged Water Jets

In order to extend the working range of high-speed submerged water jets and to improve its accuracy confidence, the jet working characteristics are studied under the condition of widely varying ambient pressures P₂. The erosion tests were systematically carried out by using aluminum-alloy specimens, and the aspects of the cavitation clouds around the jets were simultaneously observed. Clearly, the pressure P₂ drastically affects the aspects of cavitation and its occurrence region. With increasing P₂, the length of the cavitating jet decreases, so that the standoff distance, where the most severe erosion appears, shifs upstream. In short, the intensity and the distribution of the impulsive pressures induced by the cavitating jets also drastically change with P₂. The impinging erosion characteristics are also sensitive to the standoff distance and the injection time.