钢轨铝热焊接过程传热传质行为计算流体力学数值分析  

Numerical Analysis of Heat and Mass Transfer Behaviors in Aluminothermic Welding of Rails Using Computational Fluid Dynamics

作　　者：翟明 宋宏图 罗国伟 任金雷 高松福 石孟雷 李政 ZHAI Ming;SONG Hongtu;LUO Guowei;REN Jinlei;GAO Songfu;SHI Menglei;LI Zheng(Metals and Chemistry Research Institute,China Academy of Railway Sciences Corporation Limited,Beijing 100081,China;Department of Track,Communication&Signaling and Power Supply,China State Railway Group Co.,Ltd.,Beijing 100844,China)

机构地区：[1]中国铁道科学研究院集团有限公司金属及化学研究所,北京100081 [2]中国国家铁路集团有限公司工电部,北京100844

出　　处：《中国铁道科学》2024年第5期56-66,共11页China Railway Science

基　　金：国家自然科学基金资助项目(52405443);国家重点研发计划课题(2021YFB2601000);中国国家铁路集团有限公司科技研究开发计划项目(J2021G10);中国铁道科学研究院集团有限公司院基金课题(2023YJ058)。

摘　　要：铝热焊在道岔焊接、既有线钢轨维修与断轨抢修中有着广泛的应用。由于铝热焊过程的封闭性,其温度与材料流动难以通过试验的方式进行测量。为此,运用计算流体力学的方法,采用k-ε湍流模型,结合流体体积法,并考虑液态金属的重力、浮力、表面张力与马兰戈尼效应,建立数值分析模型,对浇注和冷却过程不同时刻的传热传质行为进行定量分析,通过相分布特征研究凝固顺序,为后期优化浇注体系、构建新焊剂成分和砂型型式提供基础数据。结果表明:浇注过程中空气被裹挟进入熔池,浇注时间约为11 s,接头冷却至固相线1641 K以下的时间约为58 s;浇注开始后,不同区域最大温差约为1400 K,高温区位于轨底,低温区位于轨头;随着浇注的进行,轨头温度升高,轨腰温度先升后降,轨底温度降低;在浇注的最后阶段,不同区域温差缩小,最大约为400 K,高温区位于轨头,低温区位于轨底;在冷却过程中,轨头温度始终最高,轨底温度始终最低,按照轨底、轨腰、轨头的顺序发生凝固。Aluminothermic welding is widely used in switch welding,maintenance of existing rail lines,and emergency repairs of broken rails.However,it is challenging to measure temperature and material flow by experiment methods in the aluminothermic welding process due to its enclosed feature.To address this issue,a computational fluid dynamics method is adopted in this research.The k-εturbulence model and volume of fluid method are used,and the gravity,buoyancy,surface tension and Marangoni effect of liquid metal are considered.The numerical model is established,the heat and mass transfer behavior of the pouring and cooling stages at different times are quantitatively analyzed.Solidification sequence is studied based on the phase distribution characteristics,providing basic data for optimizing the pouring system,constructing new flux composition,and developing new sand molds in the future.The numerical predicted results show that the air is entrained into the molten pool during pouring,with a pouring duration of approximately 11 s.It takes about 58 s for the joint to cool below the solidus line 1,641 K.When the pouring process begins,the maximum temperature difference is nearly 1,400 K,with the highest temperature at the rail bottom and the lowest at the rail head.As the pouring processes,the temperature at the rail head rises,the temperature at the rail waist first increases and then decreases,and the temperature at the rail bottom drops.In the final pouring stage,the temperature difference decreases,and the maximum temperature difference is about 400 K,with the highest temperature at the rail head and the lowest at the rail bottom.During cooling,the temperature at the rail head remains the highest,and the temperature at the rail bottom the lowest,resulting in solidification occurring sequentially from the rail bottom,through the rail waist,and to the rail head.

关 键 词：铝热焊接 钢轨 传热传质 计算流体力学 数值分析 

分 类 号：U213.92[交通运输工程—道路与铁道工程]