基于计算流体动力学的矩形通道内气泡运动机理研究

Mechanism Study on Bubble Dynamics in Rectangular Pipes Based on CFD Method

基于计算流体动力学(CFD)方法,利用体积流(VOF)模型对矩形流道内单气泡及双气泡运动进行了数值模拟,并分析了其运动规律。模拟结果与前人实验观测结果相符。单气泡上升过程中经历加速上升和摆动上升两个阶段,其稳定速度与Eo数相关,摇摆阶段的气泡轨迹类似于周期性的正弦曲线。上下分布的气泡会发生聚并现象,水平对称分布的气泡上升过程中会出现规律的分离、靠近现象。研究表明:该方法能够准确地模拟气泡的运动,获得气泡运动的机理,可以作为进一步研究自然循环中不同浮升力下气泡分布机理研究的基础。

Numerical simulation on the movement of a single bubble as well as double bubbles was conducted with the VOF model based on computed fluid dynamics（CFD）. The simulation results agree well with the experimental observations. For a single bubble, the rising process includes accelerating vertically and swinging up. At the later stage, the trajectory is sinusoidal. The bubble＇s stable velocity is determined by Eo number. For the two bubbles, coalescence may occur with an up-and-down structure. On the other hand, with a horizontal distribution, the two bubbles will separate and draw near regularly. The latter two decide the radial distribution of bubbles. From the results, the CFD method can well simulate the movement of bubbles, which is the basis of further study on bubble distribution with different buoyancies in natural circulation.