Research On Fluid Flow And Heat Transfer With M-EMS In Rectangular Bloom Mold

In this dissertation,how the flow field,temperature field and surface fluctuation in a rectangular bloom mold change with casting speed,submerged depths,structure of SEN and current of the electromagnetic stirring(EMS)were studied through the methods of physic simulation of a water model and numerical simulation of a 3D model by taking a rectangular bloom continuous casting process of The Ben Steel as archetype.There are three parts in this paper.Firstly,the water model experiment of 1:1were established follow the similarity criterion,and the surface flow fluctuation and flow field were measured by DJ800 and particle image velocity(PIV)in rectangular bloom mold.Secondly,the 3D mathematical model of solidification and molten steel flow behavior in rectangular bloom mold was established based on the actual parameters of the scene.The numerical simulation is carried out by CFD software.Study the influence on the flow and temperature field in the mold by the change with casting speed,submerged depths and structure of SEN without EMS.Thirdly,the distribution and magnitude of the magnetic field was calculated by ANSYS,which was coupled to the three-dimensional mathematical model has been established to study the effect on flow and temperature fluid under the condition of current intensity,casting speed and submerged depths with EMS.Finally,to compared the difference between the flow and temperature field in the mold under different SEN with EMS.The result of water model experiment shows that: the main factors affecting the flow fluid and surface fluctuation of the rectangular bloom mold are casting speed and submerged depths.In the terms of bilateral orifice nozzle,the casting speed should be controlled around 0.7m/min,and the submerged depth should be controlled around130 mm.For the straight type nozzle,the impact depth of molten steel is relatively deep,which is disadvantage to removing central porosity and segregation.Though the measure of PIV,the bilateral orifice nozzle is more conducive to the improvement of central defect than the straight type nozzle.The results of numerical simulation of rectangular bloom mold with and without EMS showed that,under the EMS the high temperature zone moved upward in the mold,the impact depth was decreased,the average temperature of the free surface and the maximum speed was reduced,in favor of the slag inclusion and bubble floating and the central porosity and segregation removing.In the terms of bilateral orifice nozzle,the casting speed should be controlled around 0.7m/min,and the submerged depth should be controlled around 130 mm and the current intensity should be controlled in 400 A.When the current intensity increases to 400 A,the average temperature of the free surface reduces about 2.7K,and its maximum speed is reduced by about 13%.In the presence of EMS,compared with bilateral orifice nozzle and the straight type nozzle,the liquid phase point and impact depth are both shorter,the flowfield and temperature field distribution is more uniform,which is beneficial to improve the inner quality of rectangular bloom.