Transient Two-Phase Flow in Slide-Gate Nozzle and Mold of Continuous Steel Slab Casting with and without Double-Ruler El
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SIENT fluid flow phenomena in the mold during continuous casting of steel slabs are important to quality and defects in the final product. Abnormal surface flow is well known to aggravate meniscus-level fluctuations,[1,2] shear instability of the molten slag/steel interface,[3–5] and vortex formation[6,7] near the Submerged Entry Nozzle (SEN), which leads to mold slag entrainment. The mold slag entrapped by the solidifying steel shell can cause both surface defects and internal defects. These defect-related flow phenomena in the mold become more complex with argon gas, which is injected into the nozzle to prevent the nozzle clogging. Increasing argon gas volume fraction[8] or decreasing bubble size[9] can cause the jet to bend more upward, and even change the mold flow pattern from a
SEONG-MOOK CHO, Postdoctoral Research Associate, is with the Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801. BRIAN G. THOMAS, Professor, is with the Department of Mechanical Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, and is also C. J. Gauthier Professor Emeritus and Research Professor, University of Illinois at UrbanaChampaign, 1206 West Green Street, Urbana, IL 61801 Contact e-mail: [email protected] SEON-HYO KIM, Professor, is with the Department of Materials Science & Engineering, Pohang University of Science & Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 790-784, Republic of Korea. Manuscript submitted March 20, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS B
double-roll pattern to a single-roll pattern. In addition to changing the mold flow pattern, argon gas also increases surface turbulence[10] with long-term asymmetry and unbalanced transient flow in the lower recirculation region, causing bubbles to penetrate deeply.[11,12] To stabilize and optimize the transient fluid flow in the mold, ElectroMagnetic (EM) systems are often applied, especially at high casting speed. Many researchers have previously investigated the effect of EMBr on single-phase (molten steel) flow of molten steel.[13–22] Cukierski and Thomas investigated the average effect of local EMBr on steady-state flow in the mold by applying standard k–e model and plant measurements.[16] Chaudhary et al.[20] and Singh et al.[21] performed Large Eddy Simulation (LES) of the GaInSn physical model adopted by Timmel et al.,[17,18] to quantify the effect of ruler EMBr on transient mold flow pattern in the mold, having different wall conductivity; insulated and conducting walls. Some previous studies have considered the effect of EMBr on time-averaged two-phase (molten steel-argon) flow in the mold.[23–29] The molten steelargon jet flowing from the SEN deflects around the strongest region of the magnetic field, resulting in nonuniform flow under some conditions.[29] Double-ruler EMBr employs two static magnetic fields across the mold width: one ruler above the nozzle ports to stabilize the flow uprising towards the top surface and a second ruler added below t
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