On Some Positive Effects of the Swirling Flow for Continuous Casting: Numerical study on heat and mass transfer of steel casting billet moulds

Continuous caster mould is the last and important stage in the steelmaking process where inclusions can be either generated or removed. With increasing casting speed using conventional immersion nozzles critical problems, such as unstable bulk mould flow, have been noticed. Mould flux entrapment due to vortex and shearing action from the oscillating surface waves have become of particular concern. It is, therefore, necessary to have a calm inlet flow at the entrance of the mould. Recently, it has been acknowledged that a swirl blade placed at the upstream end of the nozzle effectively resolves these problems. Therefore, to increase our knowledge on swirling flow fundamental mathematical models of a billet mould equipped with a swirl blade in the nozzle have been developed. The model is used to study the effects of changing nozzle tilt angle and mould aspect ratio on heat and mass transfer in the round and square moulds. Data from water model experiments are used to verify the mathematical model predictions. A fairly good agreement between physical modeling data and predictions was found, which ensured that the numerical models are reliable.