Effects of Electromagnetic Brake on Vortex Flows in Thin Slab Continuous Casting Mold

摘要

A mathematical model has been developed to understand the vortex flows in the thin slab continuous casting mold associated with the effect of electromagnetic brake (EMBR). The molten steel flows are discharged from the bifurcated ports of the submerged entry nozzle (SEN) in the mold. Low Reynolds number k-e turbulence model is used to calculate the effective viscosity. Numerical simulation shows that the asymmetric vortices can be produced even though the geometry is symmetrical and inlet flows are steady. Asymmetric flow is caused by the perturbation of numerigal error of iteration in simulation instead of actual nozzle clogging, off-centerness of nozzle, and random turbulence etc. The vortex intensity depends on the surface velocity in the mold, which is determined by outflow angle of nozzle and casting speed. The vortices can be significantly suppressed and deformed by the application of static magnetic field, but cannot be vanished completely. The surface velocities decrease significantly with increasing coil currents, and the level of fluctuation heights in the mold becomes remarkably small. Furthermore, the aberration parts in adjacent to SEN caused by the vortices is gently calm. The vertical velocities in the lower part of the mold are suppressed and the plug like flows are formed.