圆坯结晶器电磁搅拌过程三维流场与温度场数值模拟

3D NUMERICAL SIMULATION OF FLOW FIELD AND TEMPERATURE FIELD IN A ROUND BILLET CONTINUOUS CASTING MOLD WITH ELECTROMAGNETIC STIRRING

建立了描述圆坯连铸结晶器电磁搅拌过程的三维数学模型.采用有限元和有限体积结合的方法求解Maxwell方程组和湍流Navier-Stokes方程,分析了结晶器电磁搅拌过程的磁场、流场、温度场和夹杂物轨迹特征,并考虑了励磁电磁强度和频率的影响,研究表明,磁场模拟结果与现场实测数据一致,电磁力在圆坯水平截面上呈周向分布.钢液在结晶器纵截面内形成两对回流区,且在水平截面内旋转流动;过热钢液滞留在结晶器上部区域,铸坯芯部温度迅速降低,凝固前沿温度梯度提高;大部分夹杂物积聚到结晶器上部区域旋转运动.励磁电流强度和频率对结晶器内钢液的流动、温度分布及夹杂物运动均有明显影响。

A new 3D mathematical model describing the electromagnetic stirring （EMS） in the round billet continuous casting mold was developed and the method combining the finite elementfinite volume was used to solve the Maxwell＇s equations and the turbulent Navier-Stokes equations. The characteristics of magnetic field, flow field, temperature field and inclusion trajectory during EMS were analyzed considering the influences of the exciting current intensity and frequency. The simulated magnetic field in the mold is in good agreement with the measured data in the real steel plant, the electromagnetic force is circumferential distribution at the horizontal section of billet. Molten steel forms two pair of recirculation zones in the longitudinal section of the mold and recirculates at the horizontal section. Most of superheated molten steel is stranded in the upper region of mold, the core temperature of billet reduces dramatically and the temperature gradient at the solidifying forefront of billet increases. Most inclusion particles accumulate in the upper zone of mold and do a swirllike motion. The flow behaviour, temperature distribution and inclusion motion in the mold are all influenced obviously by the exciting current intensity and frequency.