基于MPS方法的汽泡冷凝与融合特性研究

Numerical Investigation on Bubble Condensation and Coalescence of Bubble Pairs Using Moving Particle Semi-Implicit Method

移动粒子半隐式(Moving Particle Semi-implicit,MPS)数值方法在追踪汽液相界面上较传统网格方法有很大优势,本研究基于MPS方法对过冷水中单个蒸汽泡的冷凝行为进行了数值模拟研究。计算结果与Kamei的实验结果符合较好并表明,汽泡冷凝寿命与汽泡初始尺寸呈近似线性关系,低过冷度下大汽泡的变形会加速其冷凝,高过冷度下会出现冷凝波动现象。此外还利用MPS方法对汽泡对绝热融合行为进行了数值模拟,分析了汽泡在融合过程中的形变特性、融合前后汽泡上升速度的变化。本研究揭示了直接接触汽泡冷凝换热及汽泡对绝热融合行为的一些规律特征,也为MPS进一步应用于汽泡动力学数值模拟打下基础。

Moving Particle Semi-Implicit （MPS） Method has an advantage over traditional mesh- based methods in accurately trace the vapor liquid interface. In this study, we had performed a numerical simulation of single steam bubble condensation behavior. Numerical results showed a good agreement with Kamei＇s experiments and indicated that there is approximately a linear relationship between bubble initial size and bubble lifetime. A larger bubble condensation process would be accelerated by its deformation at lower degrees of liquid subcooling while the bubble condensation would induce oscillation at higher subcooling degrees. Furthermore, numerical investigation on coalescence of bubble pairs rising in the stationary liquid had been performed. The numerical results were provided for bubble shape deformation and rising velocity before and after coalescence. The present study exhibits some fundamental characteristics of steam bubble condensation and bubble pairs coalescence. It is also lay the foundation for further application of the MPS method to evaluate more complicated bubble dynamics problems.