独立可调式组合电磁制动结晶器内吹氩行为数值模拟

Numerical simulation of argon blowing behavior inside an independent adjustable combination electromagnetic brake mold

为了研究电磁参数和拉坯速度对氩气泡分布和运动、结晶器上液面钢液流速和湍动能的影响,采用数值模拟方法对独立可调式组合电磁制动(FAC-EMBr)结晶器内的吹氩行为进行研究,并且与全幅一段式电磁制动(EMBr Ruler)作用下的结果进行了对比分析。结果表明,FAC-EMBr作用下,立式磁极线圈电流强度I_V的增加可显著降低氩气泡在上回流区的速度,并改变氩气泡的运动轨迹,使其在浸入式水口附近的上液面均匀溢出。EMBr Ruler作用下,大量氩气泡随着钢液在上回流区运动并集中在浸入式水口附近溢出,容易导致高温钢液裸露而出现二次氧化现象。与施加EMBr Ruler相比,随着拉坯速度的增加,FAC-EMBr结晶器内上液面处钢液流速和湍动能显著降低,有利于稳定钢/渣界面波动和由于流速过大而造成的卷渣;EMBr Ruler作用下,虽然可以相对减少下回流气泡数量,但是很难抑制上回流气泡速度和控制氩气泡的溢出位置。

In order to study the effects of electromagnetic parameters and casting velocity on the distribution and movement of argon bubble,the velocity of molten steel on the surface of the mold and turbulent kinetic energy,the argon blowing behavior in the mold with independent adjustable combined electromagnetic braking(FAC-EMBr)was studied by numerical simulation.The results were compared with those under the full amplitude one-stage elec-tromagnetic braking(EMBr Ruler).The results indicate that under the effect of FAC-EMBr,an increase in the cur-rent intensity Iv of the vertical magnetic pole coil can significantly reduce the velocity of argon bubbles in the upward backflow region,and change the trajectory of argon bubbles,making them uniformly overflow on the top surface near the immersion nozzle.Under the effect of EMBr Ruler,a large number of argon bubbles move with the molten steel in the upward backflow region and concentrate near the immersion nozzle and are overflowing,which easily leads to the exposure of high-temperature molten steel and the occurrence of secondary oxidation phenomenon.Com-pared with the application of EMBr Ruler,with the increase of casting speed,the flow velocity and turbulent energy of the molten steel at the top surface in the FAC-EMBr mold significantly decrease,which is beneficial for stabilizing the fluctuation of the steel/slag interface and the slag entrapment caused by excessive flow velocity.Under the effect of EMBr Ruler,although the number of argon bubbles in downward backflow can be relatively reduced,it is difficult to suppress the velocity of argon bubbles in upward backflow and control the overflow position of argon bubbles.