3-D CFD simulation of a vertical direct chill slab caster with a submerged nozzle and a porous filter delivery system

A 3-D CFD model coupled with turbulent melt flow and heat transfer with solidification is developed to simulate an industrial-sized vertical direct chill (DC) slab caster for aluminum AA-1050 alloy. In a DC casting process, a melt distributor is used to feed melt to the mold to minimize the temperature gradient between the hottest and coldest areas. This study considered a new melt distributor which consisted of a submerged nozzle underneath of which there was a porous filter occupying the entire transverse cross-section of the caster. The whole assembly was placed inside the hot-top above the mold. Simulations were carried out by varying three different important parameters of the problem, namely, the casting speed from 40 to 100 mm/min, the effective heat transfer coefficient at the mold-metal contact region from 0.75 to 3.0 kW/(m2 K), and the Darcy number of the porous filter from 10−6 to 10−3. For all parametric cases, the inlet melt superheat was 32 °C and the porosity of the filter was taken as 0.4. Detail results in the form of velocity and temperature profiles, solid shell thickness, sump depth and local surface heat flux are predicted and compared.