| In the process of continuous casting,the stability of metal free surface in mold directly relate to the casting quality.But in electromagnetic continuous casting process,the free surface fluctuating due to alternating magnetic force is inevitable.Therefore it is very important to find a method to control surface fluctuation for improve the quality of casting.In this paper,using the magnetic pressure to control the free surface fluctuating was presented as a new method.Parallel straight coils and disk-shaped coils were designed as magnetic field generator.The magnetic field distribution and the electromagnetic force distribution of coils in the surface of liquid steel were researched under different parameters by the method of numerical simulation and physical simulation.In this paper,the program solving the problem that two-way coupling between magnetic field and flow field was created in order to research the deformation law of stationary liquid level and waved liquid surface under the effect of the electromagnetic force by using the two-dimensional model.The low melting point alloy Ga-In-Sn was used to simulate molten steel in experiment.The results show that the electromagnetic force in the liquid steel produced by Parallel straight coils and disk-shaped coils is parabolic and saddle-shaped distribution respectively.The electromagnetic force in the steel liquid increase with the improvement of coil number of turns、current intensity、frequency,and decrease with the improvement of space between coils and steel liquid.Under the influence of magnetic pressure,a pit is formed on stationary liquid surface.The shape of the pit is similar to the distribution shape of electromagnetic force.Under the effect of Parallel straight coils and disk-shaped coils,liquid level show arc-shaped surface and annular-shaped surface respectively.Besides,electromagnetic force will cause the liquid surface fluctuation.The intensity of fluctuation depends on the relative size of electromagnetic stirring force and electromagnetic force of constraint.If the force of constraint is greater than the stirring force,liquid level fluctuation is weak,otherwise,liquid level fluctuation is intense。There is a bulge on the surface of flowing liquid without magnetic pressure.The fluctuation of position nearby the bulge is intense.The height of liquid surface bulge has a significantly decrease,and the fluctuation extent nearby the bulge have a decreasing tendency when magnetic pressure be applied.With the current of coils continue increasing,the inhibitory effect of magnetic pressure improve and the fluctuation further weakened,The flow rate of the liquid nearby bulge is decreased,the liquid level tends to be flat,the shear flow is weakened,and it is favorable for reducing drawing slag in the mold and ladle in the continuous casting process.However,after current increase to certain intensity,the fluctuation of liquid surface don’t improve with the current increasing.A new bulge is formed in the center of the disk-shaped coil,aggravating the instability of liquid surface.Compared with the parallel straight coils,the effect of restraining the fluctuation of liquid surface is poor.So the disk-shaped coils needs to further structural and magnetic form optimization. |
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