Fluid flow, heat transfer and solidification in the mold of continuous casters during ladle change

A computational study of the transient two-dimensional turbulent fluid flow, heat transfer and solidification in continuous casting molds during the ladle change operation is presented. The computations are based on an iterative, finite-volume numerical procedure using primitive dependent variables, whereby the governing time-dependent continuity, momentum and energy equations in combination with a low-Reynolds number turbulence model are solved. A single-domain enthalpy formulation is used for simulation of the phase change phenomenon. The effect of phase change on convection is accounted for using a Darcyʹs law-type porous media treatment. It is shown that due to the time-dependence of the inlet temperature during the ladle change, the volume occupied by the liquid phase generally expands in the radial direction during each cycle, whereas the axial extent of the liquid pool shrinks due to the greater influence of the buoyancy force. The increase in size for the liquid pool depends on the casting speed and is as much as 25% when compared to the steady-state value. The size of the mushy zone does not vary greatly over the period of ladle change. The thickness of the solidified shell shrinks during the ladle change operation to some extent. Casting surface temperatures vary over the two cycles of the ladle change operation and distinct temperature rise signatures were detected.