Fluid Flow and Mechanisms of Momentum Transfer in a Six-Strand Tundish
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FLOW control is particularly difficult in multistrand tundishes employed in billet casters; steel coming from the ladle shroud suffers a bypass directly toward the closest strand providing a higher temperature in the corresponding strand mold.[1] Meanwhile, the more distant strands and their corresponding strand molds receive colder steel streams because of energy losses mainly through the bottom, top, and walls of the tundish. Steel cleanliness is also a variable because the bypassed steel directly carries many inclusions existing in the steel toward the closest mold, whereas the more distant strands receive cleaner steel resulting from inclusion floatation. Given the complex distribution of strands in these types of tundishes, researchers in the field have attempted to design flow controls through different types of furniture. Indeed, Morales et al.[2] designed a successful flow control system consisting of a pair of baffles and a turbulence inhibitor (TI) to substitute a more complex arrangement consisting of two pairs of baffles and an impact pad in a four-strand bloom linear tundish with asymmetric strand positions. Zhong et al.[3] found that specific designs of baffles induce asymmetric flows in a four-strand T-tundish AARON ESPINOZA-ZA´RATE and ALFONSO NA´JERABASTIDA, Graduate Students, MANUEL J. MACI´AS-HERNA´NDEZ, Assistant Professor, and ALEJANDRO SANDOVAL-RAMOS, Researcher, are with the Department of Metallurgy and Materials Engineering, Instituto Polite´cnico Nacional-ESIQIE, Ed. 7 UPALM, Col. Lindavista-Zacatenco, Me´xico D.F., CP 07738. RODOLFO D. MORALES, Professor, is with the Department of Metallurgy and Materials Engineering, Instituto Polite´cnico Nacional-ESIQIE and with K&E Technologies, President, Manizales 88, Col. Zacatenco, Me´xico D.F., CP 077369. Contact e-mail: [email protected] Manuscript submitted March 9, 2010. Article published online July 30, 2010. 962—VOLUME 41B, OCTOBER 2010
and underlined the importance of a TI and the specific details of baffles geometries to achieve symmetrical flows. Madias et al.[4] designed a pouring box and a pair of baffles to control steel flow in a six-strand linear tundish; although the flow pattern improved, the flow final results indicated considerable differences in the residence time distribution (RTD) curves for all strands. Jha et al.[5] tested the effect of the strand position with respect to the central tundish bottom longitudinal axis of a six-strand linear tundish equipped with a pouring box. The best strand position for a symmetric flow is the central plane with a 210-mm height box. Morales et al.[6] designed a TI with an irregular geometry for an asymmetric threestrand delta tundish. These authors proved that using only a TI is good enough to provide homogenous responses to the three-strand tundish when a tracer is injected through the ladle shroud. This design proved the usefulness of TIs not only to control turbulence but also to reorient the flow. Tripathi and Ajmani[7] reported improvement of flow by rounding the corners of the tundish in the pouring box of a six-strand
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