Surface and inner quality of the slab depend on the processes inside the mould. Thus, influencing the fluid flow within the mould and the liquid crater should help to further optimize the continuous casting process and finally the product itself.The analysis of the fluid flow and the flow affection by optimized designs of submerged entry nozzles (SEN) can be carried out experimentally or by numerical simulations. Frequently, water models are used, however, their view of the real plant situation is only limited. Therefore, additional numerical CFD calculations (computational fluid dynamics) have to be carried out to describe the behaviour of the liquid steel by model approaches. The quantitative laser-optical investigations at the water model are used for the validation of the CFD calculations.In the context of the investigations CFD calculations for the steady state water flow and steel flow in the SEN and the mould of a thin slab caster are carried out on the basis of the Reynolds equations (Reynolds-Averaged Navier-Stokes equations, RANS). Preceding DPIV measurements of the fluid flow in the water model are used as validation criterion for the freely selectable CFD parameters. The turbulent flow in the SEN was calculated using the Reynolds stress model separately from the mould; the realizable and/or RNG k-epsilon model were employed for the mould. A solidification model considering the evolving solidification enthalpy and the influence of the solidification on the fluid flow by temperature dependent material properties was employed for the thermal steel calculation in the mould. In this way interactions between fluid flow and solidification are considered. The developing surface waves in the mould were determined by the conversion of the static pressure and were compared with the measured wave heights in the water model.
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