Investigation of the impact load characteristics of micro-jet induced by cavitation collapse on rigid wall surface

This study examines the micro-jet generated by cavitation collapse, a phenomenon prevalent in chemical processes, with a focus on the impact load characteristics of the micro-jet on rigid wall surfaces. The expansion and collapse of cavitation bubbles generated by electric spark near the wall were recorded using a high-speed camera. Coupled with numerical simulations, a parameter lambda, representing the ratio of bubble size to the distance from the wall, was introduced to comprehensively analyze the micro-jet morphology, velocity, impact force, and the resulting impact intensity on the wall surface. It was observed that the impact effect of the micro-jet on the wall surface is most pronounced when lambda approximate to 1. The rapidly varying impact force of the micro-jet on the wall can be approximated as the impulse due to the average force acting on the wall over an extremely short time interval Delta t. Under the condition where lambda approximate to 1, both the velocity and impact force of the micro-jet, as well as the resulting impact intensity on the wall surface, increase with the bubble size. Through impact experiments on aluminum foil, it was determined that the cross-sectional shape of the micro-jet head is circular. Identified the threedimensional shape of the micro-jet as a conical structure with a circular base. A size relationship coefficient was introduced to define the geometric model of the micro-jet. This model was based on the size relationship between the upper and lower cross-sections of the conical jet, as determined from experimental results. Key parameters affecting the impact intensity of the micro-jet were identified. The intensity values for micro-jets of different bubble sizes under the condition of lambda approximate to 1 were calculated.