Effect of Submerged‐Entry Nozzle (SEN) Design on Fluid Flow and Heat Transfer in a Thin‐Slab Steel Caster

Abstract

Occurrence of breakouts (BO) during casting of narrow slabs is observed to be influenced by the submerged‐entry nozzle (SEN) design in one of ArcelorMittal's thin‐slab casters. To understand the root cause for the BO, three‐dimensional computational fluid dynamics (CFD) models are developed to simulate steady‐state and transient molten steel flow and heat transfer in the SEN and in the CSP caster for three four‐port SEN designs (type‐ A, B, and C), among which exist two major design differences, including the presence of a top insert at SEN tube entrance and height of the flow divider at SEN bottom. CFD models are validated by water model measurements of SEN port opening velocities. Both water model experiments and numerical simulation results suggest that SEN design with a taller bottom flow divider increases both mean and variations of the upper port flow rates and large‐scale asymmetric flows in the CSP mold region. Transient heat transfer simulation results further show that this unstable biased flow in the mold increases “hot spots” near the shell around the funnel‐to‐flat transition region, which could be responsible for local steel re‐melting and potential breakout under certain critical ferrostatic pressure.