基于群体平衡原理的蒸汽发生器汽液两相流动与沸腾数值模拟

基于相似原理建立了耦合四叶梅花形支撑板的蒸汽发生器“单元管”三维物理模型。采用考虑汽泡聚合与破碎效应的MUSIG （multiple-size-group）模型描述二次侧汽泡尺度分布和水力特性，热相变模型计算二次侧汽液两相沸腾相变过程，对大亚湾蒸汽发生器汽液两相流动与沸腾过程进行数值研究。模拟结果表明，支撑板位置处汽、液相流速均急剧升高，产生射流，在离开支撑板孔口时迅速形成回流。两相邻支撑板间出现明显的汽泡由小到大的周期性变化过程，冷、热端沿程汽泡最大直径缓慢减小。二次侧平均传热系数与Rohsenow经验关联式的计算结果吻合较好。

Numerical simulation of vapor-liquid two-phase flow and boiling in steam generator based on population balance

Based on similarity principle, a three-dimensional "unit pipe" physical model is built for a steam generator coupled with quatrefoil tube support plates. A multiple size group model considering breakup and coalescence of bubbles is used to describe bubble size distribution and hydraulic characteristic in the secondary side. The process of local vapor-liquid two-phase boiling with phase change is calculated through a thermal phase change model. Numerical investigation is carried out on vapor-liquid two-phase flow and boiling of steam generator at Daya Bay Nuclear Power Plant. Simulation results show that vapor and liquid velocities rapidly increase in the support plate and jet flow appears, and when the flow leaves the support plate orifice, reflow forms rapidly. The periodic distribution from small to large bubble size occurs obviously within adjacent tube support plates and the maximum bubble diameter decreases slowly in the direction of hot and cold legs. In addition, the averaged heat transfer coefficient of secondary side agrees well with the results calculated using Rohsenow's correlation.