结晶器弯月面液渣周期性流入行为与机理解析

Periodic behavior and mechanism analysis of inflow of liquid flux around mold meniscus

把握弯月面处液体保护渣随结晶器振动的周期性流入机理与控制要素,是稳定和提高连铸坯表面质量的前提。考虑弯月面区域钢液-保护渣-空气三相的几何、接触和运动特性,建立了耦合钢液传热、坯壳凝固与液渣流动的数学模型,预测结果与实际测量以及相关报道吻合,模拟分析了液渣的周期性流动和流入行为。围绕影响保护渣流入和消耗的主要因素,重点研究了液渣流入的周期性行为,探讨了一个振动周期内液渣的流入量、流入速度与渣道宽度的变化特点。通过界定和解析弯月面附近不同区域液渣流入的贡献和规律特征,对主导液渣流入的影响因素和作用机制进行了分析。结果表明,在一个振动周期内,保护渣向渣道的流入过程分为2个阶段和2种过渡状态。在第一阶段,流入的液渣主要由靠近弯月面钢液顶部的区域提供;在第二阶段,流入的液渣基本由靠近渣圈的区域提供;处于过渡状态,2个区域液渣流入渣道的量是此消彼长的过程。在弯月面区域,水平方向速度是制约液渣流入渣道入口或远离渣道入口的主要因素,垂直方向速度是影响液渣流入区域与瞬态流入量的关键,并且瞬态流入量受矢量速度分量与渣道宽度共同的影响。在此模拟条件下,液渣在整个振动周期均流入,流入量峰值为正滑脱中期,流入量低谷在负滑脱中期至负滑脱结束之间。

Grasping the mechanism and control factors of the periodic inflow of liquid mold flux at the meniscus with the mold oscillation is the premise of stabilizing and improving the surface quality of continuous casting slabs.Considering the geometry,contact,and motion characteristics of the molten steel-slag-air three-phase in the meniscus region,a mathematical model coupling molten steel heat transfer,shell solidification,and liquid flux flow are established.The predicted results are consistent with actual measurements and related reports,and the transient periodic flow and inflow behavior of liquid flux are simulated and analyzed.Focusing on the main factors affecting the inflow and consumption of mold flux,the periodic behavior of liquid flux inflow is studied.The variation characteristics of liquid flux inflow,inflow velocity,and slag channel width in one oscillation cycle are discussed.The influencing factors and mechanism of dominant liquid flux inflow are analyzed by defining and analyzing the contribution and regular characteristics of liquid flux inflow from different area around the meniscus.The results show that in one oscillation period,the inflow process of mold flux into the slag channel is divided into two stages and two transition states.In the first stage,the inflowing liquid flux is mainly provided by the area close to the top of the molten steel on the meniscus.In the second stage,the inflowing liquid flux is provided by the area near the slag rim.In the transition state,the amount of liquid flux flowing into the slag channel in the two regions is a process of one ebbing and the other growing.In the meniscus area,the horizontal velocity is the main factor restricting the liquid flux flowing into the slag inlet or away from the slag inlet,and the vertical velocity is the key to affecting the liquid flux inflow region and the transient inflow,and the transient inflow is jointly affected by the vector velocity component and the width of the slag channel.Under this simulation condition,the liquid flux flows into the slag channel throughout the oscillation cycle,the peak value of inflow is in the middle of the positive strip,and the valley of inflow is between the middle of the negative strip and the end of the negative strip.