基于二阶矩闭合模型的液态金属圆管混合对流数值研究  

Numerical Investigation of Turbulent Mixed Convection of Liquid Metal in Inclined Tube Based on Second-order Differential Heat Flux Model

作　　者：郭跃峰 苏兴康 王冠 陈起健 顾龙 GUO Yuefeng;SU Xingkang;WANG Guan;CHEN Qijian;GU Long(School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China)

机构地区：[1]兰州大学核科学与技术学院,甘肃兰州730000

出　　处：《原子能科学技术》2025年第2期360-371,共12页Atomic Energy Science and Technology

基　　金：中国博士后科学基金面上项目(2023M731458);甘肃省自然科学基金青年基金(23JRRA1099);国家资助博士后研究人员计划(GZB20230278)。

摘　　要：液态金属反应堆以低普朗特数液态金属为冷却剂,其在燃料组件内的流动存在混合对流状态,浮力引起的自然对流对液态金属对流换热具有重要影响。本文基于OpenFOAM开发二阶矩闭合模型(DHFM),并引入浮力项,采用SST-k-ω-DHFM模型研究NaK在不同倾斜角度、不同壁面热流的管道内的混合对流特性。研究结果表明:雷诺数Re较大时,强迫对流为影响对流传热的主要因素,浮力引起的自然对流忽略不计,轴向惯性力在对流换热中起主导作用;Re较小时,倾斜角度引起的浮力项改变引起自然对流强度的改变,影响液态金属对流传热,此时自然对流占主导作用,具体表现为温度、横向流分布扭曲、不均匀性。随着Re的减小,湍动能k逐渐减小,温度脉动kθ逐渐增大。Re较小时,轴向局部努塞尔数Nu_(local)随倾斜角度的增大而增大,增幅约为1.3%~3.5%。随着Re的增加,自然对流的影响减弱,倾斜角度引起的Nulocal差异也不显著。当液态金属的流动以自然对流为主时,壁面热流的增加有助于增强自然对流对传热的影响,表现为Nu_(local)增加,增加幅度约为1.05%~11.55%。本文结果可为液态金属混合对流特性研究提供数据,丰富液态金属混合对流特性研究。Liquid metal reactors,widely used in advanced nuclear systems,utilize liquid metals with low Prandtl numbers as coolants.The flow of liquid metal within the fuel assembly often exists in a mixed convection regime.In such systems,natural convection caused by buoyancy plays an important role in influencing the heat transfer characteristics of the liquid metal.In this research,a second-order differential heat flux model(DHFM)was developed based on OpenFOAM,and a buoyancy term was introduced to study the mixed convection characteristics of sodium-potassium(NaK)alloy in a pipe with different inclination angles and different wall heat flux.The distribution of temperature,velocity,turbulent kinetic energy k,temperature fluctuation kθwere investigated.The temperature distribution and transverse flow in the x and y directions were showed,exhibiting asymmetry with changes in the inclination angle.It is shown that forced convection is the main factor affecting heat transfer of liquid metal,and natural convection caused by buoyancy is negligible and axial inertia force plays a leading role in convective heat transfer when Re is large.When Re is small,natural convection plays a dominant role,and the inclination angle and wall heat flux affect heat transfer of liquid metals,which manifests itself as distortion of the temperature and transverse flow distributions,and inhomogeneity.With the decrease of Re,the k gradually decreases and the kθgradually increases.When Re is small,Nulocal increases with the increase of inclination angle,and the increase is about 1.3%-3.5%.With the increase of Re,the influence of natural convection is weakened,and the Nu_(local) difference caused by the inclination angle is not significant.When the liquid metal flow is dominated by natural convection,the increase of wall heat flux helps to enhance the influence of natural convection on heat transfer,which is manifested as the increase of Nu_(local),the increase range is about 1.05%-11.55%.This research not only provides data on the mixed convection

关 键 词：二阶矩闭合模型 浮力项 倾斜角度 OPENFOAM 

分 类 号：TL334[核科学技术—核技术及应用]