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使用开源流体动力学程序库OpenFOAM对竖直圆管内超临界压力RP-3对流传热进行数值模拟,研究重点为起始加热段的传热恶化现象。本文选择k-ε-v~2-f和k-ωSST两种低Re数湍流模型进行计算并与实验数据进行对比,讨论了两种模型对于高壁面热流条件下传热恶化现象的预测能力.通过对流场及温度场的分析对起始加热段传热恶化现象给出机理解释,最后考察了变物性及浮升力的影响。结果表明:k-ωSST模型无法模拟传热恶化;k-ε-v~2-f模型能够定性描述起始加热段内壁温的迅速升高。由流体密度变化及重力引起的浮升力作用是导致起始加热段传热恶化的重要原因。
OpenFOAM is used to simulate the convective heat transfer in supercritical pressure RP-3 in vertical tubes. The emphasis is on the heat transfer deterioration in the initial heating zone. In this paper, two kinds of low-Re turbulence models k-ε-v ~ 2-f and k-ωSST are selected and compared with the experimental data. The predictive ability of the two models for heat transfer deterioration under high wall heat flow conditions is discussed. Through the analysis of the flow field and the temperature field, the mechanism of the heat transfer deterioration in the initial heating zone is explained. Finally, the influence of the variable physical properties and the floating force is investigated. The results show that the k-ωSST model can not simulate the heat transfer deterioration. The k-ε-v ~ 2-f model can qualitatively describe the rapid increase of the inner wall temperature in the initial heating zone. The effect of the buoyant force caused by the variation of fluid density and gravity is the important reason that leads to the deterioration of heat transfer in the initial heating section.