Numerical investigations of influences on the flow in a vertical twin roll strip caster for stainless steel

摘要

Twin roll strip casting is a near net shape method for the production of metal sheets directly from the liquid phase.The thickness of the strips is in the range of several millimeters. One benefit of this method is the short length of the plant and the large saving of energy, because there is no need for reheating and milling of the steel.This results in lower costs in comparison to conventional continuous casting. Because of the high casting speeds in the range of 1 m/s and the thin shape of the product, the flow and the heat distribution inside of the casting pool are crucial for a successful process and the quality of the strip.The flow was earlier investigated in a full-scale water model of a twin roll strip caster in industrial scale, where a modular submerged entry nozzle was successfully used to create different flow regimes inside of the pool.To take the influence of the heat distribution and the solidification into account, the process was numerically simulated with Ansys Fluent. The surface-motion of the pool, especially the shape of the meniscus, is also very important for the strip formation, because the thickness of the strip is directly addicted to the contact length.Due to the transient nature of the turbulent, multiphase, non-isothermal fluid flow problem with solidification within strongly changing cross-sections, the modelling is a complex task. The VOF-method is implemented to capture the multiphase flow. Furthermore the solidification is modelled using an enthalpy-porosity method.