基于CFD方法的矩形窄缝通道内过冷流动沸腾模型研究  

Model Investigation of Subcooled Flow Boiling in Narrow Rectangular Channel Using CFD Method

作　　者：刘凯 李林峰 王明军[1,2] 章静[1,2] 田文喜[1,2] 秋穗正[1,2] 苏光辉[1,2] LIU Kai;LI Linfeng;WANG Mingjun;ZHANG Jing;TIAN Wenxi;QIU Suizheng;SU Guanghui(State Key Laboratory on Power Engineering and Multiphase Flow,Xi’an Jiaotong University,Xi’an 710049,China;School of Nuclear Science and Technology,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学动力工程多相流国家重点实验室,陕西西安710049 [2]西安交通大学核科学与技术学院,陕西西安710049

出　　处：《原子能科学技术》2022年第10期2041-2050,共10页Atomic Energy Science and Technology

基　　金：国家重点研发计划(2018YFE0116100)。

摘　　要：板状燃料元件中的矩形窄缝通道具有宽高比大的几何特征,高度方向速度梯度大、分布陡峭,发生过冷沸腾时,近壁面汽泡运动行为将受其影响而改变,其中汽泡滑移现象对沸腾换热影响较大。本文针对矩形窄缝通道中的汽泡滑移行为,构建了包含滑移热流的壁面热流分配模型,并建立机理性的汽泡受力模型和滑移模型计算汽泡脱离直径、浮升直径和滑移距离等辅助参数,开发了一套适用于矩形窄缝通道内向上流动沸腾的壁面沸腾模型。选用Nuthel窄缝通道沸腾实验进行数值模拟验证,结果表明:本文模型可以较好地预测1~4 MPa中低压工况窄缝通道向上流动沸腾的壁面过热度,最大误差相比RPI模型由80%降低至17%;蒸发热流份额和近壁面空泡份额相比RPI模型更低。The plate-type fuel assembly with the advantages of high specific power of active zone and compact structure has been widely adopted in many research reactors and material irradiation test reactors.The narrow rectangular channel in plate-type fuel assembly has the geometric characteristics of large aspect ratio,resulting in large gradient and steep distribution of velocity in the height direction.When the subcooled boiling occurs,the bubble behavior near heated wall will be affected,and the bubble sliding phenomenon has a great influence on the boiling heat transfer.In this paper,a wall heat flux distribution model considering the sliding heat flux was built and quenching heat flux was redefined as the sensible heat released by the solid wall under the dry spot.The bubble stress analysis model and sliding model based on theoretical and semi-empirical expressions were established to calculate essential auxiliary parameters including bubble departure diameter,lift-off diameter and sliding distance.A wall boiling model suitable for upward flow boiling in the narrow rectangular channel was developed.After that,the numerical simulations under different operating conditions were performed against the Nuthel flow boiling experiments in narrow rectangular channels for model verification.The results show that the model developed in this paper can better predict the wall superheat degree of upward flow boiling in the narrow rectangular channel under medium and low pressure conditions in the range of 1-4 MPa.Compared with the RPI model,the wall temperature calculated by the developed model in this paper is much higher,and the maximum error of wall superheat in the boiling region decreases from 80%to 17%in the simulated conditions,indicating that the wall boiling model considering the sliding heat flux can describe the flow and heat transfer characteristics of upward flow boiling in the narrow rectangular channel more accurately.As for the heat flux distribution,the sliding heat flux and single-phase convective heat flux cal

关 键 词：矩形窄缝通道 滑移热流 汽泡受力分析 过冷流动沸腾 

分 类 号：TL33[核科学技术—核技术及应用]