Effects of nozzle structure on the underwater cavitation characteristics of net clothes cleaning equipment

In order to understand the mechanism and influencing factors of high pressure jet cavitation of nozzle in a submerged environment, this study has focused on the evolutionary process of cavitation bubbles and combined finite volume method with mixed multi-phase flow model to analyze the cavitation, velocity distribution, and experimental cavitation intensity of fishing net cleaning equipment. The results show that the cavitation inception, growth, and collapse primarily occurred in the peripheral region of the flow field. The shape of cavitation erosion zone is the shape of ring on the test sample target. Several small dense erosion pits were densely distributed in the ring-shaped erosion zone and erosion marks were observed in the center. The cavitation erosion intensity is greatly affected by the nozzle structure, and compared with inlet diameter D=4-6 mm nozzle, the maximum vapor volume fraction of D=3 mm nozzle increased by 6.4% to 19.5%. The nozzle outlet enlargement angle greatly increased the cavitation intensity. The nozzle with an outlet angle of 30° exhibited an optimal cavitation erosion performance . With the same nozzle necking diameter and the aspect ratio n=3-6, the increase of the aspect ratio increases the cavitation intensity of the nozzle, and compared with aspect ratio n=4-6 nozzles, the maximum volume fraction of nozzle increased by 16.9%; The larger the nozzle outlet diameter d is, the less the influence degree of the aspect ratio on cavitation is; The influence degree order of nozzle structure, nozzle diameter D, outlet angle α and the aspect ratio n for cavitation intensity is α>D>n.