薄板坯连铸凝固过程中宏观偏析的数值模拟

Numerical Simulation of Macrosegregation in Thin Slab in Continuous Casting

建立了连铸凝固宏观传输过程的温度场、溶质场、紊流流场模型 ,并对其进行了耦合求解。模拟分析了薄板坯凝固过程和宏观偏析的形成过程。计算表明 ,浸入式水口射流冲击到结晶器窄壁后形成上下两股回流 ,液相的紊流流动对传热、传质等都有显著的影响。随凝固的进行 ,液相中的溶质不断富集 ,最终在铸坯的中心区域形成宏观偏析。采用Schneider等的溶质传输模型 ,计算了固相溶质逆扩散对糊状区及固相溶质分布的影响。

A fully coupled model was developed to describe the temperature field, solute field and turbulent flow field in continuous casting process, which was used to predict the solidification of the thin slab and the formation of the macrosegregation. The results show that injection flow from the submerged entry nozzle impacts the narrow face of the crystallizer to divide into upper and lower backflows. The turbulent flow has a significantly effects on heat transfer and solute transfer. The macrosegregation is formed in central area of the billet resulted from the continuous enrichment of solute during solidification process. The solute transfer model of Schneider is employed to predict the effects of the counter diffusion on the distribution of solute in the mushy zone and solid phase.