LBE下降流场中传热管微裂纹处蒸汽泡动力学数值模拟研究  

Numerical simulation of steam bubble dynamics at microcrack in LBE descending flow field

作　　者：董伟健 丛腾龙 朱俊志 肖瑶 邹旭毛 顾汉洋[1] DONG Weijian;CONG Tenglong;ZHU Junzhi;XIAO Yao;ZOU Xumao;GU Hanyang(School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200030,China;China Nuclear Power Technology Research Institute,Shenzhen 518000,China)

机构地区：[1]上海交通大学机械与动力工程学院,上海200030 [2]中广核研究院有限公司,深圳518000

出　　处：《核技术》2022年第12期93-105,共13页Nuclear Techniques

基　　金：国家自然科学基金(No.51876128、No.12135008);黑龙江省自然科学基金项目(No.YQ2020A003)资助。

摘　　要：铅铋冷却快堆(Lead-Bismuth Cooled Fast Reactor)蒸汽发生器传热管发生破口(Steam Generator Tube Rupture,SGTR)事故时,高压水蒸汽进入一次侧高温液态金属。根据破口位置和尺寸不同,破口泄漏行为可能涉及破前泄漏(Leak-Before-Break,LBB)、单相临界流或两相临界流,不同形态的水在高温液态金属作用下发生不同形式的热质传输行为,对铅铋冷却快堆的安全运行具有重要影响。针对SGTR不同阶段,开展了系列研究,重点关注管内干涸阶段SGTR,传热管微裂纹低流量单相蒸汽渗入螺旋管束间液态铅铋合金(Lead-Bismuth Alloy,LBE)下降流场中汽泡动力学行为。基于VOF(Volume of Fluid)模型建立蒸汽-LBE两相流动及相界面捕捉数值模拟模型,研究高温LBE向下运动的流场中的单根传热管和3×3管束表面蒸汽泡生长与脱离行为。研究结果表明:汽泡在下降流场中的动力学行为与静止或向上流动的液体中的行为存在较大区别,蒸汽泡受LBE下降流场和浮力的作用脱离裂纹处后可能会沿着传热管表面滑动,在部分工况下蒸汽泡可能形成覆盖传热管表面的蒸汽膜或在管束区域内大量堆积,给LBE流动稳定性和蒸汽发生器换热带来不利影响。[Background]When steam generator tube rupture(SGTR)occurs in the lead-bismuth cooled fast reactor,high pressure water/steam flows into the primary side filled with high temperature liquid metal.According to the location and size of the rupture,the leakage behaviors of the rupture may involve leak-before-break(LBB),singlephase critical flow or two-phase critical flow.Under the action of high temperature liquid metal,different forms of heat and mass transfer behaviors occur in the two-component multiphase system of water-metal,which has an important influence on the safe operation of the lead-bismuth cooled fast reactor.[Purpose]This study aims at the bubble dynamic behavior in the descending flow field of liquid lead-bismuth alloy(LBE)in the tube bundle in different stages of SGTR caused by microcrack on the surface of the heat transfer tube during the drying stage and low flow single phase steam permeates the primary side.[Methods]Based on the VOF method,a numerical simulation model of steam-LBE two-phase flow and phase interface capture was established to study the bubble growth and transport behaviors from single tube or 3×3 tube bundle in the downward flow field of high temperature LBE.The SST k-ωmodel was employed to solve the turbulence equation.The physical law of steam bubble movement was analyzed and its influence on the heat transfer and operation stability of steam generator was evaluated.[Results]The results show that the dynamics behaviors of steam bubbles in the descending flow field are quite different from these in static liquid or upward flow.The steam bubbles may slide along the heat transfer tube surface after departure from the crack under the actions of LBE descending flow field and buoyancy.The steam bubbles may form a steam film covering the heat transfer tube surface or accumulate by quantity in the bundle.[Conclusions]These phenomena adversely affects the flow stability of the LBE and the heat transfer of the steam generator.

关 键 词：铅铋冷却快堆 SGTR 下降流场 LBB 汽泡动力学 

分 类 号：TL99[核科学技术—核技术及应用]