Thermal modelling of DC continuous casting including submould boiling heat transfer

Abstract

The steady-state thermal problem associated with the direct-chill continuous casting of aluminium–magnesium (Al–Mg) alloy cylindrical ingots is solved by an efficient numerical simulation method which also includes secondary cooling with submould boiling heat transfer. A nonorthogonal control volume discretisation and coordinate transformation technique has been applied for solving the heat transport phenomena in a multi-domain framework which involves detrmination of the solid–liquid interface (solidification front) and evaluation of the thermal profile during continuous casting operation. Conservation equations are reformulated in differential–integral form in terms of the transformed coordinates. All the terms arising from the nonorthogonality of the control volume have been retained in the numerical solution methodology and a front tracking procedure has been applied based on an iterative solution scheme. Using theories of nucleate boiling with forced convection and film cooling, a methodology has been devised to evaluate the external boundary conditions in the submould region of the ingot. These concepts are incorporated into the numerical model to account for the secondary cooling conditions during ingot solidification and simulation results show very good agreement with the published experimental data.