Suppression of Free-Surface Vortex in Tundish by Rotating Stopper-Rod and Its Impact on Multiphase Flow in Mold

Abstract

The free-surface vortex at the end of tundish casting sequence induces slag carryover into the mold, which can induce reduction in metal yield, deterioration in billet quality, and disruption to production. In this paper, the results of multiphase flow behavior in both tundish and mold during the formation process of free-surface vortex calculated by large eddy simulation (LES) model the RNG k-ɛ model were firstly compared, then the effect of rotating speed of stopper-rod on vortex and mold was numerically investigated based on the LES model. The results showed that the LES model offers a more precise simulation of multiphase flow, providing a better representation of tundish swirl evolution, fluctuations at the steel/slag interface, and slag phase motion. When the rotating speed of stopper-rod is 60 r/min, the fluctuation of mold flux is minimized, with a maximum surface velocity of 0.12 m/s, a slag carryover velocity of 0.122 kg/s at the moment of vortex penetration, and the amount of residual steel is reduced by about 600 kg, the critical height of the 1st and 2nd strands is reduced by 13.5 mm and 15.5 mm, respectively, which performs clear advantage over the schemes of 0, 30, and 90 r/min. The present study can offer theoretical guidance on suppressing free-surface vortex in tundish on the premise of improving the multiphase flow in mold.