Effect of Nozzle Clogging on Bubble Movements and Slag Behaviors in a Slab Mold

Clogging in the submerged entry nozzle is a common concern during the continuous casting of Al-killed steels, deteriorating the steel quality and impeding the continuity of mold operations. Water experiments were carried out to investigate the multiphase flow in the mold under different nozzle clogging modes. Bubble measurement was achieved by projection methodology using a high-speed camera. The LES-VOF-DPM model was developed based on size distributions of bubbles obtained from water modeling, to evaluate the effects of nozzle clogging on bubble capture by solidifying shell and slag-metal interface behaviors. The results show that clogging at the nozzle groove inhibits the bubble break-up by turbulent flow. Bubbles remaining in large sizes float vertically, leading to concentrated impacts on the slag-metal interface. Clogging at two nozzle ports increases the entry velocity under a constant casting speed. Due to the broken effect of the strong turbulent flow, 9.23 pct of the bubbles are smaller than 0.5mm. Small bubbles tend to reach a narrow face following the entry flow and then are trapped by the solidifying shell. The present study provides a comprehensive approach to evaluating the life cycle of SEN.