Physical and Numerical Simulations on the Unsteady Three-Phase Flow in a Continuous Casting Tundish During Ladle Changeover Process
摘要
The rapid change of the slag-metal interface and flow pattern is the main factor causing the abnormal increase of inclusions. Therefore, a 1/4-scale water model experiment and three-phase simulation was established to study the flow pattern transition, slag entrainment and slag eye evolution in a two-strand continuous casting tundish under quasi-steady, ladle changeover, and re-steady process. The results showed that the flow and phase distribution of the water model were effectively predicted by the three-phase simulations, tracked the interface behavior between water, slag and gas, and explained these phenomena observed in the water model. At the quasi-steady process, five high-speed flow regions and two large vortices were observed, with volume fractions of 16.24, 36.74, and 47.02 pct for the dead, plugged, and well-mixing regions, respectively. The ladle changeover process, containing the emptying and filling stages, caused drastic changes in the height of the water-oil interface. In the filling stage, the high-speed reflux flow impacted the slag-metal interface near the shroud, so the fluctuation, slag eye and slag entrainment were observed. The slag eye area reached a maximum value of 19000 mm2 at 480 seconds. An elliptical slag droplet, characterized by a major axis length of 7.255 mm and a minor axis length of 4.314 mm, was detached from the slag layer at 401 seconds. In addition, the flow field in the tundish returned to a re-steady flow state after maintaining a steady flow rate for 165 seconds.