| Electromagnetic flow control technology is a non-contact flow control technology.It is widely used to control the flow of molten steel in the continuous casting mold.This paper proposed a new method to optimize the flow field in slab continuous casting mold with a combination of EMBr and EMS(CBS),namely applying a linear EMS in the meniscus region to rotate meniscus flow,and applying EMBr to restrain the mainstream flow.By adjusting the stirring position and related operating parameters,the intensity and distribution of CBS are changed,finally,activated the flow in the meniscus and restrained flow in nozzle outlet zoneThe whole simulation process is conducted in accordance with magnetic field,flow field(no magnetic field),EMBr only and EMS only,and CBS.Firstly,3 dimensional models of electromagnetic device and mold is established,finite element software ANSYS is used to calculate the magnetic field,software Excel and Matlab is used to processed the magnetic field.Secondly,import the magnetic field into MHD module in software Fluent and for calculation of flow field.Finally,the calculated data is plotted by Tecplot and Origin.The calculation parameters are mold width,current(including EMBr current and EMS current),frequency,casting speed,position of EMS.The results of magnetic field show when the yoke is connected,the static magnetic field Bstatic in EMBr zone introduced into EMS zone is considerable which interferes with the molten steel flow in the meniscus,however,the magnitude of the traveling EMS field introduced into the EMBr zone is small,and the influence is weak.comparison results of the electromagnetic force in the EMS zone,Ftraveling and Ftra x sta are larger than Fstatic and Fsta x tra,in which Ftra x sta largest.This is not suitable for controlling the flow field in the meniscus of the mold.By disconnecting the yoke,the Bstatic can be greatly reduced,thereby Ftra x sta reduced,the interference on the EMS zone can be reduced,and when the coil current phase of U=0°,the EMS is bestThe results of flow field calculation show that,(1)the flow control effect is good in casting speed range from 1.0m/min to 1.4m/min,not ideal in casting speed 1.8m/min,whose meniscus speed is close to the critical speed of entrapment.(2)in casting speed 1.0m/min,flow in mold in the position 1 and the position 2 is quite good,while it is the best in position 1 in casting speed 1.4m/min.(3)the mainstream velocity and turbulent kinetic energy,the intensity of impacting narrow surface is suppressed when the EMBr current is increased,while the lower backward flow is weakened,and the upper backward flow is at first enhanced,and then suppressed.When casting speed is 1.0m/min,EMBr current intensity should be larger than 600A,when casting speed is 1.4m/min,850A.(4)the higher the EMS frequency,the weaker the penetration depth of the magnetic field,the greater the velocity in the downflow side,and frequency 2Hz is the best in this paper.(5)the higher the EMS current intensity,the counter flow side extends more along the narrow edge of the mold to the downstream side,the vortex enhanced,and the lower place the mainstream impactd on the narrow side.To sum up,the optimal parameters in casting speed 1.0m/min,EMBr current intensity larger than 600A,EMS current intensity 500A,frequency 2Hz,stirring position 1 or 2;In casting speed 1.4m/min,EMBr current intensity is 850A,EMS current intensity 700A,frequency 2Hz,stirring position 1. |
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