采用 Speziale-Sarkar-Gatski (SSG)雷诺应力模型对液态金属在堆芯子通道内的流动、传热过程进行计算流体动力学(Computational Fluid Dynamics, CFD)模拟，研究雷诺数(Re)、分子普朗特数(Pr)、格拉晓夫数(Gr)、节径比(P/D)等无量纲参数对湍流换热的影响。比较无量纲对流换热系数(Nu)可以看出，CFD 预测值与实验值及经验关系式符合得较好。对各种不同无量纲参数下的计算结果进行分析发现：在 P/D 和 Re 数相同条件下，三角形子通道的壁面温度分布比方形更均匀，换热情况更好；提高 Re 数，增大 P/D，选用 Pr 数大的冷却剂，可有效改善温度和换热的周向分布不均情况；在 Re 数大于10000的条件下，浮力对液态金属换热的影响可忽略不计。%Background: Liquid metal has been proposed as the coolant of the fourth generation nuclear reactor and the accelerator driven sub-critical system. Due to its low molecular Prandtl number (Pr), liquid metal differs from other coolants like water or gas in heat transfer. Purpose: This study aims to investigate the character of heat transfer of liquid metal inside the reactor core. Methods: Speziale-Sarkar-Gatski (SSG) Reynolds stress model was applied to the Computational Fluid Dynamics (CFD) prediction of liquid metal flow and heat transfer inside the sub-channels of the reactor core. Effect of different dimensionless parameters, e.g. Reynolds number (Re), Pr, Grashof number (Gr) and pitch-to-diameter ratio (P/D) on the turbulent heat transfer calculated results was investigated. Results: The dimensionless convective heat transfer coefficient (Nu), predicted by the CFD method, agrees well with the experimental data and the empirical relations. Conclusion: Based on the analysis of various dimensionless parameters, it is found that the heat exchange performs better in triangular fuel assembly sub-channels than that in square sub-channels, under the same condition of P/D and Re. The inhomogeneous circumferential distributions of temperature and heat transfer can be effectively improved by increasing Re and P/D or choosing coolants with large Pr. When Re is larger than 10 000, the buoyancy effect on liquid metal heat transfer could be ignored.
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