改进的VOF方法对气液两相流振荡流动和传热计算的影响

在VOF(volume of fluid)模型的基础上,引入level set函数,形成CLSVOF(coupled level set volume of fluid)模型对气液两相流的振荡流动和传热过程进行数值模拟,与只采用VOF模型模拟的结果进行对比分析,并与实验结果相比较.结果表明:无论是针对矩形空腔中两相流的振荡流动和传热,还是活塞冷却油腔中机油的振荡冷却过程,采用CLSVOF模型都可以更为准确地模拟气液两相流的振荡流动规律,传热系数计算值也与实验结果保持了更高的一致性.对于活塞冷却油腔中机油的振荡冷却计算,随着转速即雷诺数的增大,传热系数计算值的误差开始增大.在极限转速3 000r/min时,CLSVOF模型的误差为3.8%,VOF模型的误差为7.5%,CLSVOF模型的误差增幅稳定在0.6%左右.CLSVOF模型的误差较小且误差增幅稳定,说明其计算准确性更高.

Effects of modified VOF method on gas-liquid two-phase flow oscillating flow and heat transfer calculation

On the basis of VOF (volume of fluid) model, the level set function was introduced, and the CLSVOF (coupled level set volume of fluid) model was formed to numerically simulate the process of gas-liquid two-phase oscillating flow and heat transfer. The simulation results of CLSVOF model were compared with that of VOF model, and also compared with the experimental results. The results show that either for the oscillating flow and heat transfer process of two-phase flow in rectangular cavity, or for the oscillating cooling process of engine-oil in piston oil cooling gallery, CLSVOF model can more accurately simulate the oscillating flow rules of gas-liquid two-phase flow, and the calculation values of heat transfer coefficient consist with experimental results much better. For the oscillating cooling calculation of engine-oil in piston oil cooling gallery, with the increase of speed, i .e. Reynolds number, the error of calculation values of heat transfer coefficient increase accordingly. At the ultimate speed of 3000r/min, the error of CLSVOF model is 3.8%, and the error of VOF model is 7.5%; the error increase amplification of CLSVOF model is about 0.6%. The error increase amplification of CLSVOF model is relatively small and stable, so its higher calculation accuracy can be illustrated.