Effect of Stopper-Rod Misalignment on Fluid Flow in Continuous Casting of Steel
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Misalignment of metal-delivery systems can cause asymmetric fluid flow in the mold region of continuous casters, leading to abnormal surface turbulence, insufficient superheat transport to the meniscus, slag entrainment, inclusion entrapment, and other quality problems. This work investigates the effect of stopper-rod misalignment on nozzle and mold flow velocities in a conventional continuous casting process using both a water model and a computational model. Three stopper-rod configurations are studied (aligned, front misaligned by 2 mm, and left misaligned by 2 mm). The 3-D steady k–ε finite-volume model matched well with impeller probe measurements of both velocity and its fluctuations. Negligible asymmetry was found near the narrow faces. Asymmetry close to submerged entry nozzle is the main cause of vortex formation observed in all cases. The left-misaligned stopper-rod produces a shallower jet with a higher flow rate from the right port, leading to higher surface velocities on the right surface. This produced substantially more large vortices on the left side. The asymmetry produced by the nozzle length bore diameter ratio of ~21 in this work is consistent with the theoretical critical entrance length of ~24 for turbulent pipe flow.
KeywordsTurbulent Kinetic Energy Surface Velocity Casting Speed Vortex Formation Submerged Entry Nozzle
The authors thank POSCO and Shin-Eon Kang, POSCO Technical Research Laboratories for providing the water model, H.N. Bae for helping with the water model experiments, and ANSYS Inc. for supplying FLUENT. Support from the Continuous Casting Consortium, University of Illinois at Urbana-Champaign, POSCO, South Korea (Grant No. 4.0002397.01), and the National Science Foundation (Grant No. DMI 05-00453) is gratefully acknowledged.
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