单个浸没孔气泡动力学特性的数值模拟

核电厂发生严重事故时可利用池洗效应去除泄漏的放射性气溶胶。对池洗过程进行两相数值模拟研究是有必要的，在使用两相计算流体力学（CFD）程序计算之前需要确定气泡注入点处的边界条件。基于整合池洗研究（IPRESCA）项目框架和流体体积法（VOF），对单个浸没孔气泡动力学特性进行数值模拟研究，捕捉浸没孔处气泡的大小、形状和脱离频率，并对气泡注入速度对气泡脱离频率的影响进行敏感性分析。利用DBSCAN聚类算法获得了气泡质心高度，并计算得到了不同高度的气泡上升速度。给出了平均空泡份额沿z轴方向的分布，以及平均空泡份额和平均混合速度在不同高度平面沿水平及径向的分布。 

Numerical Simulation of Gas Injected Bubble Dynamics from Single Submerged Orifice

In severe accidents of a nuclear power plant, the released radioactive aerosols can be removed by pool scrubbing effect. Two-phase numerical simulation of the pool scrubbing process is necessary. The boundary conditions at the bubble injection point need to be determined before using the two-phase CFD program. Based on the framework of Integration of Pool scrubbing Research to Enhance Source-term Calculations (IPRESCA) project and the volume of fluid (VOF) method, a numerical simulation of gas injected bubble dynamics from single submerged orifice was carried out. Bubble size, shape, and detachment frequency at the orifice were captured. Sensitivity analysis of the influence of bubble injection speed on bubble detachment frequency was carried out. The bubble centroid height was obtained by DBSCAN clustering algorithm, and the bubble rising velocity at different heights was calculated. The distribution of the mean void fraction along the z-axis direction and the distribution of mean void fraction and mean mixture velocity along the horizontal lines and radius in central plane at different height are given.