Mathematical Simulation On Flow And Heat Transfer Behaviors Of Mold Flux In Continuous Casting

In continuous casting process, mold flux is added on the top surface of the molten steel at regularly time, then it absorbs heat from the molten steel,sinters and melts to form a steady three layer structure:flux power layer,sintered layer and liquid slag layer. And then the molten flux is drawn into the gap between the steel shell and the mold under the effect of the mold oscillation and the moving steel shell to provide lubrication and thermal uniformity.In the normal continuous casting process, it is important to controll the liquid flux layer thickness to balance the slag melting rate and the stable and continuous slag infiltration into the gap and consumption. The infiltration of liquid slag into the mould-strand gap at the meniscus region decides the slag consumption and the slab quality. Thus, during continuous casting, a steady supply of liquid slag and infiltration has important significance to promote the uniform distribution of liquid slag film, adequate heat transfer and reduce the friction.Revealing and analyzing heat transfer and flow behavior of mold slag is meaningful to improve the slab quality. In this paper, bassed on heat transfer theory, viscous fluid mechanics, mathematical computional models have been developed to study the heat transfer and fluid flow behavior of liquid slag above the molten steel, velocity of liquid slag at transverse section of slag film and slag consumpution.Firstly, based on the equipment parameters and process conditions of an arc caster for slab continuous casting, a two-dimensional mathematical model has been developed. The Navier-Stokes equations and energy equation are solved in this model, and the temperature distribution and fluid flow of molten flux are also calculated. The effects of the liquid flux layer thickness, the temperature dependent viscosity and the bottom shear velocity are investigated.Then, a mathematical computational 2-D flow model has been developed according to the characteristics of the mold meniscus area to study fluid flow in this region based on the Navier-Stokes equations and Menter et al.'s k-co SST equations. The effects of mold osciallation and download movement of the strand on the molten flux flow behavior are considered.The steady meniscus shape is calsulated using the Bikerman equation. Then the transient fluid flow, the slag/steel interface fluctuations and the mean velocity of molten slag at transverse section of slag film and slag consumpution in an oscillation cycle and the effect factors:casting speed, stroke and frequency are investigated. This work will be useful to research the complex metallurgical behavior of the mold flux during the continuous casting process.