TURBULENT FLOW SIMULATIONS IN BIFURCATED NOZZLES : EFFECTS OF DESIGN AND CASTING OPERATION

Bifurcated nozzles are used in continuous casting of molten steel, where they influence the quality of the cast steel slabs. The present study performs two and threedimensional simulations of steady turbulent (K-ε) flow in bifurcated nozzles, using a finite-element (FIDAP) model, which has been verified previously with water model experiments. The effects of nozzle design and casting process operating variables on the jet characteristics exiting the nozzle are investigated. The nozzle design parameters studied include the shape, angle, height, width, and thickness of the ports and the bottom geometry. The process operating practices include inlet velocity profile and angle, and port curvature caused by erosion or inclusion buildup. Results show that the jet angle is controlled mainly by the port angle, but is steeper with larger port area and thinner walls. The degree of swirl is increased by larger or rounder ports. The effective port area, where there is no recirculation, is increased by smaller or curved ports. Flow asymmetry is more severe with skewed or angled inlet conditions or unequal port sizes. Turbulence levels in the jet are higher with higher casting speed and smaller ports. † FADY M. NAJJAR, formerly Research Assistant, Department of Mechanical and Industrial Engineering, University of Illinois, Urbana, IL is with the National Center for Supercomputing Applications, University of Illinois, 5600 Beckman Institute, 405 North Mathews, Urbana, IL 61801. BRIAN G. THOMAS, Associate Professor, is with the Department of Mechanical and Industrial Engineering, University of Illinois, 1206 West Green St., Urbana, IL 61801. DONALD E. HERSHEY, formerly Research Assistant in the same department, is with G.E. Aircraft Engines, One Neumann Way, M.D. A106, Cincinnati, OH 45215.