| Molten steel flow in continuous casting mold plays an important role in theeliminating of inclusions and entrapment of mold power, improving uniform growthof initial solidification shell, preventing the breaking out as a result of the streamwashing local the initial solidification shell and inducing surface crack of the slaband so on. It is an effective way to apply static magnetic field for controlling theflow of molten steel in mold. Up to now, even though plenty of numerical simulationhas been done, it was fairly lack of experimental research to verify the result ofnumerical simulation, leading to the lack of the knowledge about the flow and effectof magnetic field on it. The aim of this dissertation is to investigate the flow in themold under a static magnetic field experimentally.Based on similarity theory, a mercury (Hg) model with the electric conductivityand flow characteristic similar to molten steel was used, which is according to a steelmill’s continuous casting mold of slab as prototype. The Ultrasonic DopplerVelocimeter (UDV) was adopted to measure the velocity of the liquid metal in themold. The flow behavior of the melt under various patterns of magnetic fieldconditions has been studied particularly.In this paper FC-Mold, FC-MoldII, Narrow-Side-Patter EMBr, Jet-Patter EMBr,Compound Patter EMBr with Narrow-Side and Jet and H-Patter EMBr conditionshave been explored by measuring the flow field and surface fluctuation. The brakingeffect of magnetic field was deep analyzed about flow field in mold. The influenceof magnetic flux density (B), immersion depth of nozzle (H), casting rate andlocation of magnets on the flow field, wave of free surface, impacting depth, andimpacting density to narrow side in mold have been investigated experimentally.It is shown by studying the flow of liquid metal in mold under FC-Mold conditionthat the horizontal flow rate of level increased, vertical flow rate near narrow facedecreased, wave of level weakened, impacting depth became deeper, impacting intensity to narrow side of mold strengthened after increasing magnetic flux density.It is shown by studying the flow of liquid metal in mold under FC-MoldIIcondition that the enhancement of upper magnetic field could reduce the horizontalflow rate of level and height of level wave. The horizontal flow rate of level wassmallest when both upper magnetic field (BU) and lower magnetic field (BL) were0.5T, the wave height of level was biggest when BU=0T, BL=0.5T. The impactingdepth became deeper because of application of BLand the value of its depth becamebigger at the same time if BUwas strengthened continuously. Impacting intensity tonarrow face of mold strengthened with application of the magnetic field.The physical simulation of the flow of liquid metal in mold has been studied underthree irregular-shaped magnets (Narrow-Side-Patter EMBr, Jet-Patter EMBr,Compound Patter EMBr with Narrow-Side and Jet) conditions. With application ofNarrow-Side-Patter EMBr, the horizontal flow rate of level decreased, horizontalflow stability was strengthened, wave of level weakened, impacting intensity tonarrow side of mold decreased, impacting depth became shallower and plug flowcould easily come into being if magnetic flux density increased. With application ofJet-Patter EMBr, the horizontal flow rate of level increased, wave of level weakenedand then increased, impacting depth became shallower and impacting intensity tonarrow side of mold decreased when magnetic flux density increased. Whenapplication of Compound Patter EMBr with Narrow-Side and Jet, the horizontalflow rate of level increased, wave of level increased, impacting depth becameshallower if magnetic flux density strengthened.It is known by studying the flow of liquid metal in mold under H-Patter magneticfield condition that the flow field in mold could be controlled effectively even if themagnetic flux density was small. The horizontal flow rate of level decreased, waveof level strengthened, impacting depth became lower when increasing magnetic fluxdensity.It is shown by studying the location of magnets in mold under FC-Mold condition that the horizontal flow rate of level increased, vertical flow rate near narrow faceincreased, wave of level was strengthened, impacting depth became deeper,impacting intensity to narrow face of mold was strengthened when the location ofmagnets moved downward.With application of EMBr, the horizontal flow rate of level decreased, wave oflevel weakened, impacting depth became lower, impacting intensity to narrow sideof mold was strengthened when immersion depth of nozzle became deeper. ToFC-MoldII, the horizontal flow rate and wave of free surface were biggest,impacting intensity to narrow side of mold was also strongest (BU=0T, BL=0.5T andBU=0.18T, BL=0.5T) when H=28mm. The direction of flow rate of level waschanged to flow toward narrow side of mold when H>37mm.When casting rate increased, the horizontal flow rate of level increased, wave offree surface became violent, impacting depth and impacting intensity to narrow sideof mold were strengthened. |
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