In continuous steel casting, the clogging of submerged entry nozzles (SENs) by non-metallic inclusions such as alumina is a serious issue that degrades product quality. Previous studies have suggested that unsteady flow in barrel-shaped SENs may help suppress inclusion adhesion, but the mechanism remains unclear. This study aims to clarify the dominant flow structures responsible for adhesion suppression by applying dynamic mode decomposition (DMD) to time-resolved velocity fields obtained from CFD simulations of the barrel-shaped SEN. The analysis revealed that strong unsteady flow is induced by fluctuations in the reattachment position of the separated jet occurring downstream of the contraction section. Among the extracted DMD modes, a representative mode showed periodic structures extending along the nozzle wall, which expanded and contracted while rotating circumferentially. This indicates the presence of swirling flow inside the SEN. Such flow is known to enhance near-wall shear and reduce particle residence time, contributing to the suppression of inclusion adhesion. These results suggest that the swirling motion captured by DMD plays a key role in the anti-clogging effect of barrel-shaped nozzles.
YAMADE et al. (Wed,) studied this question.
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