NUMERICAL INVESTIGATION OF THE INFLUENCE OF AIR GAPS UPON THE SOLIDIFICATION IN A ROTARY CASTER

The paper numerically investigates the influence of the formation of i nterfacial air gaps along the heat transfer surfaces in an aluminum ro tary-strip easter. This thermal resistance significantly reduces the c ooling capacity of the casting process leading to conditions that can cause, in addition to structural non-uniformities, break-outs of inter ior molten metal, with serious consequences to process continuity and production rates. The numerical model couples interfacial heat transfe r to the thermal development in the easter as the numerical solution p roceeds. The numerical model is benchmarked using available experiment al and numerical results for a horizontal twin-belt easter. The govern ing equations are formulated in generalized coordinates to provide fle xibility when dealing with different easter geometries. For the energy equation a fixed-grid enthalpy formulation is used allowing, with a s ingle set of equations, the description of the liquid, the two-phase m ushy, and solid regions.