Experimental Study of the Mold Flow Induced by a Swirling Flow Nozzle and Electromagnetic Stirring for Continuous Castin
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, BERND WILLERS
, GERNOT HACKL, YONG TANG,
This study focuses on an experimental investigation of the fluid flow in round bloom continuous casting using a 1:3 model of the industrial casting process. A swirling flow nozzle, represented by the specific design of the RHI Magnesita GYRONOZZLE, is used to produce a swirling motion in the cylindrical mold. The test section is integrated into the Mini-LIMMCAST facility at HZDR, which is operated at room temperature using the ternary alloy GaInSn. Systematic measurements of horizontal and vertical velocity profiles are performed by means of the Ultrasound Doppler Velocimetry. The second part of the study focuses on the interaction between the flow driven by the GYRONOZZLE and concurrent electromagnetic stirring in the mold (M-EMS) by applying rotating magnetic fields (RMFs) at different magnetic flux densities. The effect of the GYRONOZZLE on the flow pattern inside the mold is examined with and without superimposed RMFs and compared to those of a standard single-port nozzle. The measurements reveal that the GYRONOZZLE induces a swirling flow in the whole mold. It is further shown that the influence of a simultaneously applied RMF is mainly restricted to the lower part of the mold since the transport of angular momentum to the top is suppressed by the jets pouring out from the GYRONOZZLE. https://doi.org/10.1007/s11663-018-1491-5 Ó The Minerals, Metals & Materials Society and ASM International 2019
I.
INTRODUCTION
OVER the past few years, research activities and technological development on optimizing continuous casting with respect to high process efficiency and excellent product quality have focused increasingly on controlling the fluid flow in the tundish, the submerged entry nozzle (SEN), and the mold. It is well known that serious casting defects could arise from adverse flow patterns and the unpredictable nature of highly turbulent flows. Violent behavior of the submerged jets, transient vortex structures, and low-frequency oscillations of the global flow pattern or turbulent flow near the meniscus endanger the quality of the cast product. In particular, single-port SENs, as they are commonly used in billet casting, produce a strong downward flow in the mold that makes the flotation and removal of inclusions and bubbles difficult. In general, two different strategies DENNIS SCHURMANN, BERND WILLERS, and SVEN ECKERT are with the Helmholtz-Zentrum Dresden-Rossendorf e.V. (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany. Contact e-mail: [email protected] GERNOT HACKL and YONG TANG are with RHI Magnesita, 8700 Leoben, Austria. Manuscript submitted September 20, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS B
are applied for flow control in continuous casting: on the one hand, the process design is improved in terms of an optimal geometry and arrangement of components such as the tundish or the SEN, and on the other hand, diverse electromagnetic actuators are used to achieve contactless tailoring of the fluid flow. Especially for the production of round and square cast geometries, a
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