中文摘要：

液态金属冷却核反应堆采用气泡泵的概念设计来提升堆芯自然循环能力。液态金属内气液两相流动特征将直接影响核反应系统一回路的自然循环能力及堆芯安全。本研究通过采用移动粒子半隐式（MPS）方法，对液态金属中单个上升气泡的气泡动力学行为进行数值模拟。分析了铅铋合金中3种初始直径不同的单个氮气泡在上升过程中的气泡形状和速度的变化趋势；对比了初始直径相同的单个氮气泡在液钾、液钠、铅铋合金、钾钠合金和锂铅合金5种液态金属中的上升行为；同时将模拟得到的气泡形状与Grace经验关系图进行了对比，验证了MPS方法数值模拟结果的正确性。

英文摘要：

The gas-lift pump in liquid metal cooling fast reactor （LMFR） is an innova- tional conceptual design to enhance the natural circulation ability of reactor core. The two-phase flow character of gas-liquid metal makes significant improvement of the natu- ral circulation capacity and reactor safety. In present basic study, the rising behavior of a single nitrogen bubble in five kinds of liquid metals （lead bismuth alloy, liquid kalium, sodium, potassium sodium alloy and lithium lead alloy） was numerically simulated using moving particle semi-implicit （MPS） method. The whole growing process of single nitrogen bubble in liquid metal was captured. The bubble shape and rising speed of sin- gle nitrogen bubble in each liquid metal were compared. The comparison between simu- lation results using MPS method and Grace graphical correlation shows a goodagreement.