液态铅铋合金在绕丝燃料棒组件子通道间湍流交混数值模拟

Numerical Simulation of Turbulent Mixing of LBE between Sub-Channels of Wire-Wrapped Fuel Assembly

液态铅铋合金(LBE)是第四代液态金属核反应堆候选冷却剂,由于LBE热物性具有一定的特殊性,亟待对LBE在燃料组件子通道中的流动与传热过程开展研究。本文对LBE在带绕丝燃料棒组件中湍流流动进行数值模拟与分析,将燃料棒壁面温度的数值模拟结果与响应的实验数据相比较,2者具有较高的吻合度,说明数学模型及数值结果具有较高的可靠性与准确性;使用湍流交混系数β表征LBE在不同子通道间、不同燃料棒间隙宽度与燃料棒直径比(S/D)结构下的湍流交混情况,结果表明,不同子通道间β波动程度具有差异性,β的大小与S/D呈负相关。基于不同S/D与雷诺数的计算结果,拟合出不同子通道间β关联式,为绕丝燃料棒三角形排列方式的燃料组件子通道分析程序开发提供交混模型。

The lead-bismuth eutectic(LBE)is a candidate coolant for the fourth generation liquid metal reactors.In view of its special thermophysical properties,its flow and heat transfer process in the fuel assembly sub-channels need to be studied.For this purpose,the authors conduct numerical simulation and analysis of the turbulent flow of the LBE in the wire-wrapped fuel assembly,and compare the numerical simulation results of the wall temperature of fuel rods with the experimental data for response.The simulation results agree well with the experimental data,indicating that the mathematical model and numerical results are highly reliable and accurate.The authors also characterize the turbulent mixing of LBE between different sub-channels at different values of the ratio of spacing between fuel rods to the fuel rod diameter(S/D),using the turbulent mixing coefficient,β.The characterization results show that the fluctuation ofβbetween different sub-channels varies and that theβvalue is negatively correlated with the S/D.Based on different calculation results of the S/D and Renolyd number,the correlation formula for theβbetween different sub-channels is obtained by fit.It provides a turbulent mixing model for the development of a sub-channel analysis code of fuel assembly consisting of wire-wrapped fuel rods arranged in triangular form.