Effect of emptying time on multiphase and mixing behaviours during grade change of a five-strand bloom tundish

Abstract

The transient three-phase flow and steel mixing during the grade change of a five-strand bloom tundish under different emptying times (ETs) were numerically investigated. Water model experiments were conducted to verify the models. The results showed that the area of steel exposure first decreases with the increase of ET within 2.4 s of refilling time, and then deteriorates with the further increase of ET caused by the strong fluctuation of steel-slag interface. The exposed area tends to be stable when the refilling time is over 60 s, showing results of 50, 84 and 124 cm² when the ETs are 2, 3 and 4 min, which are substantially less than the exposed area of 310 cm²‌ when the ET is 5 min. Meanwhile, the steel mixing time decreases with the increase of ET. The proper ET should be 4 min by comprehensively considering the steel exposure and mixing behaviours.