| In continuous casting production process,the electromagnetic stirring has been a conventional equipment to improve the quality of slab.In this thesis,the solidification process of continuous casting under electromagnetic stirring is studied,which is to provide support for the optimization of the process.In continuous casting production,the solidification process of liquid steel with electromagnetic stirring is a very complex multi-field coupled problem,which is a very complicated phenomenon,including fluid flow,heat transfer,solute transfer and phase change.Numerical simulation technology is an important method to study this complex problem.Based on momentum,energy and solute conservation equations in the process of continuous casting billet solidification,a mathematical model of multi-field coupled with electromagnetic stirring was established.On the basis of studying the distribution of electromagnetic field in electromagnetic stirring,the corresponding solving strategy was proposed in this thesis.Meanwhile the simulation program was developed to investigate in the influence of electromagnetic stirring parameters on the flow velocity and solute distribution in the solidification process of continuous casting slab.This thesis mainly included:(1)Mathematical model of electromagnetic stirring was established by using ANSYS.Analysis on no load,transient state and harmonic of M-EMS and F-EMS were carried out in this thesis.The distribution of the magnetic induction intensity and electromagnetic force in continuous casting billet with the time and space variety of electromagnetic stirring is investigated.The correctness of the model is verified by comparing the simulation results with measured data from steelworks.(2)The coupled model of electromagnetic field and flow field is established.The momentum and control equation was given in continuous model.Being in form of the source terms of the equations,the electromagnetic force was participated in calculation.And the mathematical model of the magnetic fluid coupled field was established.And the governing equations were discretized by using of the QUICK formaton basis of the finite volume method.Every variable quantity was identified with numbers in order to simplify programming.The PISO algorithm in flow field solution was confirmed.(3)A multi-field coupled model of magnetic,flow,temperature and solute was established.The control equation of energy and solute conservation was given,and the coupled relationship between the control variables of each field was analyzed:the coupled relationship between the solid phase fraction,the permeability and the solute concentration in two phase region.The four fields coupled model of flow field,heat and solute distribution with electromagnetic stirring was established on the basis of(1)and(2).Fluid flow was coupled in one-way style by electromagnetic field,which was secondly developed and applied for ANSYS by VB.NET.Fluid flow,temperature field,solute field were calculated by two-way coupled sequential iterative method,and the coupled calculation of all transfer information variables through the node.(4)The macro transport model with electromagnetic stirring was calculated by self-compiled program,and the distribution of flow field and solute field under different electromagnetic stirring parameters was analyzed.The results showed that:The mean value of the electromagnetic force was the main factor that drives the flow of steel,so it was used as a load transfer to the flow field.In the practical application of the current intensity and frequency range,duringthe current intensity increased with the step of 100A,the magnetic induction intensity increased 30mT,the maximum tangential electromagnetic force of the slice increased by 2000N/m3,and the maximum speed of the slice was accelerated by 0.08m/s.With the increasing of the current frequency,the magnetic induction intensity showed a slight decrease and the increasing of the electromagnetic force in the continuous casting billet was very small,and the changing of the flow velocity of the liquid was small.Finally,the quality of solidification segregation of continuous casting slab was compared with the practical data in the same electromagnetic stirring parameters,which conformed to the actual law of change. |
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