Large Eddy Simulations of the Effects of EMBr and SEN Submergence Depth on Turbulent Flow in the Mold Region of a Steel
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duces over 95 pct of steel in the world today,[1] hence even small improvements to this important industrial process can have large economic impact. The characteristics of turbulent flow in the mold region of the caster influences the creation of surface defects, slag entrainment, and other issues related to the quality of steel. The velocity across the top surface of the mold is an important parameter affecting defect formation. A very small velocity causes reduced heat transfer and leads to hook formation, meniscus freezing, and other surface defects. On the other hand, if the top surface velocity is too large, the resulting turbulence and shear layer instability may entrain slag and form inclusions in the final product. Therefore, it is very important to choose operating conditions which produce flow patterns within an optimal operational window to avoid these problems. These operating conditions include the mold cross section, casting speed, submergence depth, argon gas injection, and electromagnetic forces. The use of KAI JIN, Graduate Student and Research Assistant, and SURYA P. VANKA, Research Professor, Professor Emeritus, are with the Department of Mechanical Science and Engineering, University of Illinois at Urbana–Champaign, 1206 West Green Street (MC-244), Urbana, IL, 61801. BRIAN G. THOMAS, formerly Research Professor, C.J. Gauthier Professor Emeritus with the Department of Mechanical Science and Engineering, University of Illinois at Urbana– Champaign, is now Professor with the Department of Mechanical Engineering, Colorado School of Mines, 1610 Illinois Street, Golden, CO. Contact email: [email protected] Manuscript submitted July 1, 2016. Article published online September 9, 2016. 162—VOLUME 48B, FEBRUARY 2017
electromagnetic force is an attractive method to dynamically control the mold flow due to its easy implementation by simply changing the electric current in the coils of the device. The electromagnetic forces are commonly generated by applying a magnetic field near the mold region. A static magnetic field is attained by passing direct current (DC) through electromagnets, which induces a Lorentz force field that acts against the flow. Thus this concept is usually referred to as an electromagnetic braking (EMBr) system. Based on the DC electromagnets shape and location, there are three typical types of static magnetic field configurations: local,[2–7] single ruler[7–12] and double ruler.[12–17] The difference between these configurations as well as the use of moving magnetic fields are discussed elsewhere.[18] In this work, we focus on the double-ruler configuration which is widely used in industry and commonly known as the flow control mold (ABB Automation Technologies).[19] In the double-ruler configuration, two rectangular magnetic fields across the entire mold width are generated, with one positioned near the meniscus and the other below the nozzle ports.[13–18] This configuration is able to slow down[13,17] or to speed up[12,16] surface velocities in the mold region, and has been reported to decrease high-
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