中文摘要：

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。

英文摘要：

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.