单汽泡沸腾过程数值模拟的研究

摘要

The single bubble boiling process was simulated by means of the Level Set equation in the Comsol Multiphysics software,the microstructure network was established,boundary conditions were provide,and the mass,momentum,energy and Level Set equation were solved. The satisfied simulation results were acquired. The changes of the holdup,pressure field,velocity field and temperature field with time were studied. The influences of contact angle and wall effect on the bubble departure diameter and bubble growing period were investigated. It was showed that,when the contact angle was bigger than 12°,the bigger the contact angle,the bigger the departure diameter and the longer the bubble growing period. But the bubble departure diameter was constant when the contact angle was less than 12°. As the heating foil diameter was less than the bubble departure diameter,the bubble was not easy to grow up and leave the wall. When the heating foil diameter was more than the bubble departure diameter,the bubble departure diameter was constant and the bubble growing period decreased with the heating foil diameter increasing.%利用Comsol Multiphysics软件中的Level Set方法对单汽泡沸腾过程进行了模拟，建立了微细结构网格，给出了边界条件，求解了质量、动量、能量和Level Set方程，得到了正确的模拟结果。分析了单汽泡沸腾过程中相含率、压力场、速度场和温度场随时间的变化规律；考察了接触角和壁面效应对汽泡脱离直径和汽泡生长周期的影响。模拟结果表明，当接触角小于12°时，汽泡脱离直径维持不变；当接触角大于12°时，接触角越大，汽泡脱离直径越大。汽泡生长周期随接触角的增大而延长。当加热装置的直径小于汽泡脱离直径时，汽泡受壁面效应的影响不易脱离；当加热装置的直径大于汽泡脱离直径时，汽泡脱离直径不随加热装置直径的增大而变化；汽泡生长周期随加热装置直径的增大而缩短。