| In the continuous casting production,the electromagnetic stirring technology of the crystallizer has become an important means to improve the quality of the billet.The molten steel is rotated by the electromagnetic torque to realize effective control of solidification structure,center looseness,center segregation,internal cracks and inclusions and subcutaneous bubbles of the billet,thereby improving the quality of the slab.Therefore,it is important to study the influence of electromagnetic stirring parameters on the magnetic field and flow field distribution in the mold.In this paper,a 160mm×160mm billet continuous casting machine of a steel plant is taken as the research object.The numerical simulation and field experiment are used to analyze the distribution law of the magnetic field and the flow field flow pattern under the electromagnetic stirring.The effects of electromagnetic stirring parameters on magnetic field and flow field distribution were studied.The core issue of this paper is how to ensure the accuracy of numerical simulation.The specific research contents are as follows:(1)Establish a mathematical model of the electromagnetic stirring magnetic field of the crystallizer and solve it with ANSYS.The electromagnetic field control equation is derived and the electromagnetic force solving equation is given.Using ANSYS,a finite element model was established using a top-down modeling approach and SWEEP meshing.The scheme of field measurement of magnetic induction intensity was established.The accuracy of the mathematical model of the magnetic field was verified by comparing the field measurement data with the numerical simulation results.The transient distribution analysis is used to study the variation of the magnetic field distribution law with time.The harmonic electromagnetic force is used to obtain the time-average electromagnetic force,which can be transmitted to the flow field as the load.(2)Establish a mathematical model of the magnetic flux coupling field.The flow field governing equations based on continuous equations and momentum conservation equations are derived.The control equation is discretized by using the central difference format for the diffusion term and the improved QUICK format for the convection term,and the PISO algorithm based on the co-located grid is used to solve the problem.The decoupling conditions of the magnetic current coupling model are analyzed to realize the one-way coupling of the electromagnetic field to the flow field.Various turbulence models and turbulence models suitable for this topic were studied,and the treatment methods for near-wall flow problems were established.(3)Solving the magnetic current coupling model using CFX.The results of the magnetic current coupling model are analyzed.The distribution pattern of the flow field and the influence of electromagnetic stirring parameters on the flow field are obtained.Comparing the flow velocity of the solidification front molten steel under different stirring parameters with the standard speed,the optimal process parameters of the electromagnetic stirring of the crystallizer were obtained.The results show that in the horizontal plane,the magnetic induction intensity is stronger at the edge and corner of the slab,and the overall distribution is more uniform.In the central axial direction,the magnetic induction intensity is the largest at the center of the agitator and gradually decreases toward the two ends;the magnetic induction intensity in the slab The current increases and increases.When the current intensity increases by 100A,the magnetic induction intensity increases by 30mT;it increases first and then decreases with the increase of frequency;when there is electromagnetic stirring,the flow pattern of molten steel varies greatly,without electromagnetic stirring.When the flow rate is small and only a pair of circulating currents are formed in the axial direction,when the electromagnetic stirring is performed,the flow velocity is large and two pairs of upper and lower circulations are formed in the axial direction;the optimal process parameters of the electromagnetic stirring of the crystallizer studied in this subject are 400A,4Hz. |
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