Cavitating flow characteristics, cavity potential and kinetic energy, void fraction and geometrical parameters - Analytical and theoretical study validated by experimental investigations

摘要

Analytical and theoretical discussions validated by experimental investigations are presented to comprehensively study the relation between the geometrical parameters, such as the dimensionless standoff distance and nozzle geometry, and the cavity potential energy, and void fraction to improve the performance of submerged cavitating water jets. The force generated by the collapse of cavitation clouds was employed to initiate cavitation erosion in copper test samples under various hydrodynamic and geometrical conditions. The nozzle diameter and the separation distance between the nozzle and the specimen were varied in order to determine the optimal geometrical configuration, which leads to maximal erosion rate. The damaged specimens were investigated using optical and scanning electron microscopy (SEM). The obtained results - along with selected, previously published works from the literature - verify the analytically derived formulas, which emphasize the connection between the dimensionless standoff distance, and the cavitation intensity, potential energy, void fraction, and indicate the existence of an optimal dimensionless standoff distance for maximal erosion rate. Formulas to conveniently compare the efficiency of a cavitating jet based on energy consumption and dimensionless standoff distance are also presented and demonstrated. The influence of nozzle diameter and standoff distance on the kinetic energy and the specific energy consumption was clearly observed.