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-e turbulence 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 11s.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
Key words
Aluminothermic welding/Rail/Heat and mass transfer/Computational fluid dynamics/Numerical analysis
维普
万方数据