轴对称通道内超临界水对流换热数值模拟

Numerical simulation on heat convection of supercritical water flow in axisymmetric channel

为了研究高性能轻水堆堆芯冷却通道内超临界工质流动与换热特性,采用Fluent软件对竖直上升环形通道内超临界水与管壁间的换热过程进行数值模拟研究。通过计算结果与实验结果的对比,评估了不同网格数量、壁面第1层网格参考高度和湍流模型对数值模拟准确性的影响。对5个不同湍流模型进行对比计算。针对3种热流密度进行堆芯流动换热计算。模拟结果表明:随着网格数量的增加和壁面第1层网格参考高度的降低,预测准确度逐渐提高,但当壁面第1层网格参考高度小于0.07后,预测准确度与其无关;与其他湍流模型相比较,标准k-ω模型和剪切压力传输(SST)k-ω模型都能预测传热恶化现象,SSTk-ω模型较标准k-ω模型计算结果更为准确;近壁面区域物性的剧烈变化是引起传热强化及传热恶化的主要原因。

The heat convection process between the supercritical water and pipe wall in a vertical annular channel is numerically simulated by Fluent to investigate the flow and thermal characteristics of the working fluid in cooling channels of a high performance light water reactor. The influence of different grid numbers,the height between the adjacent grid and the wall and turbulence models on the accuracy of numerical simulation is evaluated by the comparison between the numerical and the experimental data. Five turbulent models are compared by computation. The core heat convection simulation is carried out for three different heat flux densities. The simulation results show that the accuracy of the forecast improves with increasing grid number and decreasing height between the adjacent grid and the wall,and the accuracy of the forecast has nothing to do with the height between the adjacent grid and the wall less than 0.07;the standard k-ω model and the SST k-ω model can predict the heat convection deterioration of the core either,and the SST k-ω model shows better accuracy;the significant change of physical properties in the near wall area is the main reason for heat convection enhancement or heat convection deterioration.