板坯连铸结晶器液面的周期性瞬态特征

Periodic transient level fluctuations in continuous casting mold of slab

采用1∶1水模型和工业试验研究了常规板坯连铸结晶器液面的瞬态特征。研究发现,常规板坯结晶器液面存在"周期性畸变"。该现象表现在液面每隔20~30 s出现约5 s的畸变。畸变期间窄面处液面凸起,宽度1/4处液面凹陷且表面流速达到极大值,易导致卷渣。定义上次液面畸变结束到本次畸变结束时间为畸变周期。水模型结果显示,提高拉速畸变周期减小,而提高水口浸入深度与倾角液面畸变周期增大,但改变这些参数不能消除周期性畸变。对液面畸变周期的影响程度为:水口倾角>拉速>水口浸入深度。工业试验也证实液面周期性畸变的确存在。适当增大水口倾角有利于减少液面周期性畸变导致的卷渣。

A full scale water modeling combined with industry experiments was carried out to investigate the transient characteristics in the continuous casting mold of slab. The results of water modeling show that the periodic level distortion exists in the traditional slab casting mold. This phenomenon involves about 5 s level distortions of the mold level every 20-30 s. The mold level near the narrow faces raises up but depresses at the quarter location with the maximum surface velocity during this distortion period. The distortion period is defined as the interval between the last distortion-ending to the latest distortion ending. The results also shows that increasing the casting speeds may decrease the distortion periods while raising the SEN depths and angles can promote these periods. Changing these casting parameters could not eliminate the level distortion,however can alter their periods. Furthermore,the effects on level distortion periods decreases from SEN angles,casting speed to SEN depths. The industrial experiments also confirms the existence of the periodic level distortions. Increasing the SEN angles may reduce the slag entrapments caused by the periodic distortions.