水口浸入深度对结晶器内钢液流场与温度场的影响

Effects of Nozzle Submerged Depth on Flow and Temperature Field of Molten Steel in Mold

采用软件CFX4.3和新的结晶器入口速度赋值方法,数值模拟了水口浸入深度150～450 mm时板坯结晶器内钢液的速度和温度分布。结果表明,随着水口浸入深度的增加,结晶器内钢液流场和温度场的基本特征保持不变,但上部回流区范围增大,下回流区的涡心下移;窄面所受的向上和向下的最大剪切力的值变大,峰值出现位置下移;窄面热流密度峰值的位置下移,浸入深度为300 mm时,热流密度的峰值最小;射流对窄面撞击点的位置也随之下移;弯液面处钢液的水平速度呈逐渐减小的趋势,反映自由表面波动的F数逐渐变小。对于侧孔倾角为向下15°、结晶器截面为1 200 mm×250 mm、拉坯速度为1.0 m/min的工况,最佳的浸入深度为300 mm。

Velocity and temperature distribution of molten steel in mold for slab with nozzle submerged depth 150 - 450 mm have been simulated by using software CFX4.3 and a new method to give the velocity at inlet of mold. Results showed that with increasing nozzle submerged depth, the basic pattern of flow and temperature field of steel didn＇ t change, but the upper backflow region enlarged and the center of lower backflow region moved down ; the value of down- and upward maximum shearing stress at nan＇ow face increased and the position of occurred peak value moved down; the position of peak heat flux on narrow face moved down, and with submerged depth 300 mm, the peak value was minimum; the position of impingement point also moved down; and the horizontal velocity of molten steel in meniscus zone and the F number which expresses free surface fluctuation decreased. For 1 200 mm × 250 mm slab with casting speed 1.0 m/min and nozzle port angle 15°, the optimum nozzle submerged depth is 300 mm.