带定位格架的5×5棒束通道内过冷沸腾流动传热数值研究

Numerical Analysis on Flow and Heat Transfer of Sub-cooled Boiling in the Channel of 5×5 Rod Bundles with Spacer Grids

基于流体体积函数(VOF)两相流模型,通过在控制方程中加入适当的质量源项和能量源项,建立了过冷沸腾模型,利用该模型对5×5定位格架棒束通道内的过冷沸腾现象进行数值模拟,研究了有无过冷沸腾现象2种工况下的传热特性以及入口速度、入口过冷度等因素对燃料组件内传热特性的影响。结果表明:有过冷沸腾现象时流体的传热效果优于无过冷沸腾现象,在有过冷沸腾现象时,总体上通道内传热系数与入口速度呈正相关,与入口过冷度呈负相关;在局部区域,相变传热占据主导因素,过冷沸腾程度越强,流体的传热效果越好。

To numerically simulate the sub-cooled boiling in the channel of 5×5 rod bundles with spacer grids,a sub-cooled boiling model was established based on the volume of fluid(VOF)two-phase flow model,by adding appropriate mass and energy source terms into the governing equation,so as to study the heat transfer performance under conditions with and without sub-cooled boiling,and to analyze the effects of inlet velocity and inlet under-cooling degree on the heat transfer characteristics in the fuel bundles.Results show that the heat transfer effectiveness of the two-phase flow with sub-cooled boiling is better than that without sub-cooled boiling;in the case with sub-cooled boiling,the overall heat transfer coefficient in the channel would be positively correlated with the inlet velocity and negatively correlated with the inlet under-cooling degree;in local regions,the higher the degree of sub-cooled boiling,the better the effectiveness of heat transfer.