Multiphase phenomena in the application of in-mold electromagnetic stirring in continuous casting were discussed through cold experiment using mercury and numerical simulation by using two fluid model. The result revealed the critical flow rate of argon injected in the submerged entry nozzle, which leads to the change in flow pattern in the bulk liquid metal inside the mold pool. This change does not have a large effect on the flow driven by in-mold electromagnetic stirring because the Lorentz force acts mainly in the vicinity of solidifying shell except for the case of large amount of the argon flow rate. The particle behavior under in-mold electromagnetic stirring in the vicinity of the solidifying shell was also discussed by solving near-wall fluid flow and employing the particle tracking method, which showed the important effect of lift force by the increase in velocity inclination near the solidifying shell by electromagnetic field.

Effect of different types of in-mold electromagnetic brake (EMBr) technique, which forms a local magnetic field and a level magnetic field in the width direction of a mold, on the fluid flow phenomena in the strand pool was examined. A mercury model experiment revealed that the level magnetic field developed a pluglike flow in the strand pool, of which flow could not be obtained by the local magnetic field. Surface velocity near the meniscus could be stably controlled with the level magnetic field, while in the case of the local magnetic field, this surface velocity was greatly affected by the nozzle condition. Numerical analysis clarified the characteristics in the distribution of an induced electric current density and Lorentz force, and explained the flow behavior with the local and level magnetic fields, respectively.KEY WORDS: continuous casting; fluid flow; electromagnetic brake (EMBr); mercury model experiment; numerical analysis; magnetohydrodynamics (MHD). trolled at a constant level, according to the principle of the U-shaped tube. The mercury then is pumped up into the tundish above the strand pool. From there, it is discharged again into the pool through a pipe, which serves as an immersion nozzle. In the lower part of nozzle, the acrylic pipe is utilized for electric insulation. The flow rate of the mercury through the immersion nozzle is adjusted by a stopper in the tundish. Two types of DC magnets were placed around the vessel to investigate the effect of the magnetic field conditions on the flow. One DC magnet type forms a DC magnetic field partially crossing the broad face of the mold. The other one forms a level magnetic flux density in the width direction of the pool. The resulting flow of mercury then was used to predict the molten steel flow. The distribution of magnetic flux density which each DC magnet forms, was measured without mercury circulation. Figures 3(a) and 3(b) show the vertical and horizontal distribution of the magnetic flux density throughout the pool of mercury in the case of the local magnetic field and the level magnetic field, respectively. Table 1 gives the experimental conditions adopted in the mercury model experiment. The total amount of mercury in the pool was about 2 tons. The level magnetic field's center was 135 mm below the meniscus. The local magnetic field's center was 150 mm below the meniscus and 150 mm from the center of the pool. In addition, the effect of an angle of nozzle port, 15 degrees downward and 45 degrees downward respectively, on the fluid flow was examined. These experiments will be referred to as nozzle condition A and nozzle condition B, respectively, throughout the remainder of this paper. Figure 4 shows the relationship between the discharged flow and DC magnet in each magnetic field condition. With the local magnetic field, the crossing length in the magnetic area is longer in the nozzle condition A than the one in the nozzle condition B. With the level magnetic field, in both of the nozzle conditions A and B, the discharged flow directly c...

A markedimprovement of the surface quality of casts and a break-through

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