棒束结构气冷换热的湍流模型适用性评价  

Applicability Evaluation of Turbulence Models for Gas-cooled Heat Transfer of Open Lattice Structure

作　　者：刘宇浩 孙倩 方浚麟 叶子申[1] 孙俊[1] LIU Yuhao;SUN Qian;FANG Junlin;YE Zishen;SUN Jun(Institute of Nuclear and New Energy Technology,Tsinghua University,Beijing 100084,China;Beijing Institute of Space System Engineering,Beijing 100076,China)

机构地区：[1]清华大学核能与新能源技术研究院,北京100084 [2]北京宇航系统工程研究所,北京100076

出　　处：《原子能科学技术》2024年第8期1732-1741,共10页Atomic Energy Science and Technology

摘　　要：高功率空间核电源采用棒束气冷堆具有质量轻等优势,其紧凑的栅格结构以及流动雷诺数(Re)较低的特点会影响堆芯的流动换热规律,采用CFD开展数值分析时需评价湍流模型的适用性。在气体工质棒束结构流动换热实验的基础上,利用ANSYS Fluent建立了试验段的数值模型,针对入口Re在688~2 986之间的实验工况,选择4种湍流模型开展了数值模拟,对比了加热棒包壳温度实验测量值与计算值。结果表明,4种湍流模型计算的棒温整体上均低于实验值,其中转捩SST模型结果与实验值最接近,整体平均偏差为-2.0%,较好地反映了横流等特征,可用于Re在2 000左右的棒束气冷堆芯热工水力数值计算。The open lattice gas-cooled reactor presents a lightweight option for high-power space reactor power systems.The background of this study is a space reactor featuring a rod bundle core structure,with helium as the coolant.The typical Reynolds number at the core inlet is around 2000.Reynolds average numerical simulation(RANS)is a commonly used computational fluid dynamics(CFD)method.The essence of the RANS method lies in turbulence models.Each turbulence model has its particular useful scenarios and needs to be chosen based on the specific working conditions.The helium-cooled rod bundle reactor is distinguished by its tight lattice structure and low flow Reynolds number.These features influence the flow and heat transfer characteristics in the reactor core.Consequently,when performing thermal-hydraulic analysis using CFD,it is essential to evaluate the applicability of turbulence models.Experiments of flow and heat transfer in 37-rod bundle structure were conducted,using electrically heated rods of the same size as the fuel rods and nitrogen as the experimental coolant.Based on these experiments,the convective heat transfer within the test section was numerically simulated using ANSYS Fluent,selecting four turbulence models:Realizable k-εwith enhanced wall treatment,SST k-ω,transition SST,and Reynolds stress model with enhanced wall treatment.The operating conditions for numerical calculations had inlet Reynolds numbers ranging from 688 to 2986,all with uniform power distribution.By comparing the experimental measurements and calculated values of the heating rod cladding temperatures,the applicability of the four turbulence models was evaluated.Simultaneously,the differences in local flow field simulations by these models were observed,and an analysis was performed to understand the reasons behind the discrepancies in cladding temperature calculations among the different models.The results show that all four turbulence models generally underpredict the rod cladding temperatures.Among these models,the transition

关 键 词：气冷堆 棒束结构 湍流模型 低雷诺数 流动换热 横流 

分 类 号：TL424[核科学技术—核技术及应用]