Numerical Simulation Study of Droplet Impact Process on Free Liquid Surface

Atomization and spraying of pressurizer are crucial for safely operation of nuclear power equipment. Study on the process of spray droplets impacting the free surface of the pressurizer can start from the impact of single droplet on the liquid surface, revealing fundamental patterns and phenomena. This provides a theoretical foundation for study on the continuous impact of droplets on the liquid surface during pressurizer spraying. Numerical simulations and analyses were conducted using Fluent's DPM-to-VOF (DTV) method. The accuracy of the DTV method was validated using the Volume of FluiD (VOF) approach. The study systematically investigated the influence of droplet diameter and initial velocity on the main dimensions of liquid pits and columns. It comprehensively revealed evolution process of liquid surface fluctuation, accurately captured details of liquid film fluctuation. Results indicate that increasing droplet diameter or velocity intensifies surface disturbances, resulting in larger pit sizes, taller columns, and potential occurrences of primary and secondary droplets. In addition, a comprehensive analysis of flow distributions under various conditions revealed significant surface disturbances in regions of high Weber and low Froude numbers. Quantitative analyses of $ H_{\mathrm{K}}/d_0 $, $ L\mathrm{_K}/d_0 $, and $ H\mathrm{_Z}/d_0 $ variations with $ We $ and $ Fr $ provide an improtant theoretical basis for understanding and optimizing pressurizer spraying process.