Physical Model Research Of Low-Frequency Traveling Magnetic Field On Bubble Distribution And Surface Fluctuation In Mold

Argon-blown protection in the mold is a common operation technology in slab continuous casting production. The flow field in the mold is a two phase flow of gas-liquid due to the gas blowing in the nozzle. Thus, it is very important to control the size and distribution of argon bubbles and the level fluctuation in the mold.In this paper, we developed a physical model based on slab continuous casting mold of Baoshan second steel mill. The scale between the model and the prototype is1to5.The alloy of Pb-Sn-Bi and argon gas were employed to simulate the two phase flow of the molten metal and argon gas. The resistance probe and laser liquid level instrument were applied to measure the distribution of argon gas bubbles and the level fluctuation in the mold with and without EMLS (ElectroMagnetic Level Stabilizer) with different operation parameters, such as magnetic flux density, gas flow rate and casting speed.The experimental results show that the quantity of bubbles near the narrow face in the mold increases with the increasing gas flow rate and casting speed. The distribution of gas bubbles in the mold changes when EMLS is applied. The impact depth of the bubbles becomes lower, the distribution of the gas bubbles becomes equal between the1/4width of the mold and the nozzle, and the number of gas bubbles reaching the narrow face decreases, which are good for reducing the captured bubbles by the solidified shell. As for the large bubbles, the number increases when magnetic field is imposed with the different gas flow rate.Most of the large bubbles are detected near the nozzle under the free surface, and there is few large bubbles in the deep area of the molten metal. Thus, the aggregation and flotation of bubbles can be enhanced by imposing traveling magnetic field. Meanwhile, the level fluctuation near the1/4width of the mold is also enhanced when gas flow rate and casting speed are increasing. And the level fluctuation of the free surface became weaker when traveling magnetic field was imposed. On the condition of this paper, when the magnetic flux density is0.098T1is the best.