Finite Element Analysis of Electromagnetically Driven Flow in Sub-mold Stirring of Steel Billets and Slabs.

Abstract

This paper describes a new method for solving coupled three-dimensional electromagnetic and fluid flow equations in induction systems and its application to electromagnetic stirring in continuous casting of steel. This method is based on the differential-integral potential formulation of the electromagnetic field, and is capable of computing the field for any given stirrer configuration without solving the magnetic field in free space. The turbulent flow in the melt is represented by time averaged Navier–Stokes equation together with k-ε turbulent model. The finite element formulation of the governing equations is also presented. Computed results were presented for the electromagnetic force distribution, velocity and turbulent parameters in rotary stirring of billets and linear stirring of slabs during continuous casting of steel. For rotary stirring, it was found that the electromagnetic forces are confined to the region surrounded by the stirrer, and the effective flow region is about twice the length of the stirrer and the flow exhibits weak axial velocity component. It was also found that the flow is turbulent with a maximum intensity of about 15% of the mean velocity, and decays rapidly above the edges of the inductor. For linear stirring of slabs, the spatial variation of the force field along and across the slab was found to generate a more complex flow pattern than predicted by two-dimensional analysis. The turbulent intensity was found to increase monotonically in the direction of the traveling force field.