重力对单气泡生长特性的影响

采用VOF(Volume of Fluid)多相流模型,通过用户自定义函数UDF(User Defined Function)实现相变过程中质量和能量的输运,对微重力条件下尺寸为10 mm×10 mm×25 mm的矩形通道的池沸腾现象进行数值模拟,得到了微重力及常重力作用下单个气泡生长特性的差异.模拟结果表明,微重力条件下气泡周围的流线与温度场的分布有显著差异;由于表面张力作用,微重力下的气泡脱离特性与常重力下不同;在微重力条件下,气泡直径的变化比较复杂,并与重力加速度的大小有关;Marangoni流对微重力下的流动影响很大,使换热系数波动,而且波动的幅度随重力加速度的减小而增大.

Effects of Microgravity on the Characteristics of Single Bubble Growth

Based on the previous experiment and the VOF(Volume of Fluid) multiphase model, the growth characteristics of a single bubble was numerically investigated,on the condition of microgravity, for the section size of 10 mm×10 mm×25 mm rectangular channel of pool boiling.The transportation of mass and energy during the phase change is implemented by adding source term to the mass and energy equations with User Defined Function(UDF).The results show that under the microgravity condition,the streamline and the temperature field distribution around the bubble have difference;due to surface tension,the bubble under microgravity and normal gravity are different from the bubble detachment;under the condition of microgravity,the change of bubble diameter is more complex,and the heat transfer coefficient fluctuate,the increase of microgravity will enlarge the amplitude of fluctuations.