9th ECCC European Continuous Casting Conference – ECCC 2017

Slag entrainment is a challenging problem to control during continuous casting process. From fluid dynamics viewpoint, it mainly occurs due to (I) the instability of the fluids interfaces at the top of the mold and (II) vortex formation around the sub-merged entry nozzle (SEN). Both mechanisms are complex phenomena involving surface instability, vortex interactions with the metal-slag-air interface, deformation of the slag layer and its entrainment into the molten metal in the form of small droplets. Numerical modelling is a challenging task due to different physical scales involved in the real process. In this work a large eddy simulation - volume of fluid (LES-VOF) approach is used to investigate the flow behavior upon injection into the mold and the unsteady flow/vortex interaction with the meniscus interface. In order to validate the numerical simulation a benchmark experiment was designed to investigate the flow field in the proximity of a liquid-liquid interface. The experiment uses water and paraffinum liquidum to model the combination of liquid steel and the slag layer. While the entrainment of oil droplets can be visualized via shadowgraphy the flow field was measured via particle image velocimetry PIV. In combination these two methods allow a qualitative and quantitative comparison of the unsteady flow characteristics with the CFD results. To quantify the agreement of numerical and experimental results, we compare the findings on different scales, like the global flow behavior, velocity profiles at different inflow conditions and the velocity fluctuations and interface dynamics at the liquid-liquid interface. The general agreement of CFD results and experimental data is very good.