板坯连铸结晶器电磁制动和吹氩过程的多相流动现象

MULTIPHASE FLOW PHENOMENA IN A SLAB CONTINUOUS CASTING MOLD WITH ELECTROMAGNETIC BRAKE AND ARGON GAS INJECTION

利用数值模拟方法研究了高拉速连铸结晶器内电磁制动和吹氩耦合作用下的磁场、钢液流场和夹杂物行为,分析了电磁制动和吹氩量等不同工艺参数对结晶器内的钢液流动和夹杂物去除的影响规律.结果表明:电磁制动可明显减缓钢液流速(尤其是弯月面附近速度),但不利于小粒径夹杂物的上浮,5—50μm的夹杂物上浮率由无电磁制动且不吹氩时的6.7%降低到3.3%;吹氩可增加整个上回流区钢液的向上运动趋势,粒径50μm以下的夹杂物颗粒上浮率提高到8.9%;吹氩量增加使自由液面附近产生较强的漩流区,且容易产生二次涡流,直接影响液面波动情况和卷渣的发生;电磁制动和吹氩双重作用则有利于夹杂物上浮,5—50μm小粒径夹杂物去除率可达12.2%,其被凝固坯壳的捕获率可降低到64.4%.

A numerical simulation study for the multiphase phenomena of magnetic field, liquid steel flow field and inclusion behavior was described, in which the coupled effects of electromagnetic brake （EMBr） and argon gas injection in the slab continuous casting mold with high casting speed were considered. The effects of the EMBr and argon gas flow rate on the liquid steel flow and inclusion removal rate have been investigated. The results show that EMBr could slow down the flow velocity of liquid steel effectively, especially near the meniscus surface, but it had no helpful for the removal of small inclusions and the removal rate for the inclusion particles in diameter range of 5-50 μm reduced from 6.7% without EMBr and argon gas injection to 3.3% with EMBr in the mold. The argon gas injection could increase the liquid steel flow up tendency of the upper circulating area and the floating up rate of inclusion particles with the size 5-50 μm increased to 8.9%. The increase of argon gas flow rate resulted in a stronger eddy zone near the free surface especially near the submerged entry nozzle （SEN） and formed the secondary vortex flow easily, which impacted the fluctuation of free surface and the slag entrapment. The double action of EMBr and argon gas injection could increase the floating up rate of inclusions and the removal rate of small inclusions with the size 5-50 μm increased to 12.2% and the rate for inclusions to be trapped into solidified shell was reduced to 64.4%.