EXPERIMENTAL STUDY AND TEACHING ON THE MECHANISM OF NEAR-WALL CAVITATION BUBBLE COLLAPSE

Based on laser-induced cavitation bubble and schlieren observation techniques, a comprehensive experimental system was constructed. This system integrates high-speed photography with ultra-depth-of-field microscopic analysis. It enables the visualization and data acquisition of bubble collapse processes near a solid wall, as well as the resulting surface damage. The system simultaneously captures transient features like non-spherical bubble collapse, high-speed jet impact, and shock wave emission. By quantifying micron-level wall damage, it directly reveals the dynamic mechanisms of near-wall bubble collapse and induced cavitation erosion. By adjusting the dimensionless distance parameter between the bubble and the wall, the collapse modes and erosion pit distributions were analyzed under various near-wall conditions. In terms of education, this experiment utilizes visualization technology to concretize abstract mechanical concepts, such as the Rayleigh–Plesset equation and Kelvin impulse. Students are guided to participate fully in the experimental workflow, which involves fine optical path calibration, high-speed imaging, and multi-scale data analysis. This approach aims to overcome the limitations of traditional teaching in observing and describing complex transient flow fields. Furthermore, it enhances students' experimental design abilities and scientific literacy.