非能动安全壳中降膜流动与波动特性数值模拟研究

Numerical Study of Falling Film Flow and Wave Characteristics in Passive Containment

基于非能动安全壳建立了1:45的简化的二维数值模型,在保持无量纲数不变的前提下,利用流体体积函数(VOF)模型捕捉气-液交界面,分析了不同雷诺数(Re)条件下的液膜铺展状况。通过与实验结果的对比,模拟结果能够较好地反映出实验结果中的液膜波动现象,且液膜厚度的变化与Re一致;竖壁降膜过程受多种力的综合作用,波动的液膜可以分成明显的层流底层与独立波两部分,层流底层流速较低而独立波沿流动方向移动较快,随着液膜的铺展,独立波之间发生碰撞和融合并加剧液膜的波动性;随着Re的增加,层流底层的液膜厚度及独立波的振幅都有所增加,同时波动性加剧。

A simplified two-dimensional numerical model of 1:45 was established based on the passive safety system of the passive containment. Under the premise of keeping the dimensionless number unchanged, the Fluid Volume Function (VOF) model was used to capture the gas-liquid interface, and the liquid film spreading conditions under different Reynolds number Re conditions were analyzed. By comparing with the experimental results, the simulation results can better reflect the liquid film fluctuation in the experimental results, and the change of liquid film thickness is consistent with the Reynolds number. The process of vertical wall falling film is synthesized by a variety of forces, the fluid film can be divided into obvious laminar and isolated waves, the bottom flow velocity of laminar flow is low and the solitary wave moves faster along the flow direction, and the collision and fusion between the isolated waves intensifies the fluctuations of the liquid film with the spread of liquid film;With the increasing of Re, the thickness of the liquid film at the bottom layer and the amplitude of isolated wave increased, and the volatility increased.