电磁悬浮条件下金属行为数值模拟及机理研究

发布时间：2018-01-16 06:46

本文关键词：电磁悬浮条件下金属行为数值模拟及机理研究　出处：《昆明理工大学》2017年博士论文　论文类型：学位论文

【摘要】：电磁悬浮应用于火法冶金过程,可为熔滴提供无接触式的熔炼环境,避免高温条件下坩埚对于熔体的污染,提供良好反应动力学条件,进行高品质金属及合金产品的制备及冶金过程机理研究。本文旨在揭示电磁悬浮下金属熔滴的悬浮行为、振荡行为及传递行为,为电磁悬浮下熔滴行为的精确控制提供依据。建立了电磁感应模型以及与化学过程相结合的多场耦合模型,预报熔滴行为。为确保模型的准确性,利用悬浮力测量实验、电磁悬浮升温实验及电磁悬浮条件下金属熔滴的传递行为实验等路径对所建立的模型进行了验证。在较为广泛的金属(铜、钯、银、铝、金)选取范围内,借助数值模型与无因次分析方法,研究了电磁悬浮下熔滴的悬浮及振荡。以悬浮条件下的Fe-Cr-C合金脱碳过程为例,研究了熔滴的传递行为,求取了脱碳反应过程中的传质相似准数。主要结论如下:(1)电磁悬浮环境参数对熔滴悬浮行为的影响。通过建立"电磁感应模型",确立了影响熔滴悬浮行为的电磁悬浮环境参数,主要包括电流角频率w、电流强度I、试样尺寸D、材料性质ρE、μ。借助无因次分析方法表明电磁环境参数与电磁力F的关系符合公式:该式可结合数值模拟预测熔滴的悬浮条件,解释熔滴的悬浮行为变化。(2)悬浮熔滴在熔化过程中的振荡行为。建立了电磁悬浮熔滴近似弹簧模型,计算了铜、钯、银、铝、金不同材质的金属熔滴在电磁悬浮熔化过程中的振荡频率:在线圈电流范围300-450A的条件下,熔滴的振荡频率为10-30Hz之间。精确的控制悬浮条件下熔滴的振荡行为,有助于拓展电磁悬浮技术的应用。(3)以铜熔滴及Fe-Cr-C合金熔滴脱碳为例,研究了熔滴内部的传递行为。受电磁搅拌影响,熔滴内部的热量分布较为均匀,铜熔滴与Fe-Cr-C合金熔滴内部温度差在1-4K的范围内;熔滴内部的流场存在强烈的涡流,铜熔滴与Fe-Cr-C合金熔滴中的最大速度分别为0.39m/s及0.272m/s;熔滴的形变比增加,熔滴内部的涡流不断发展,电磁搅拌效果不断增强,熔滴受到的电磁升温效果也不断增强。(4)研究了电磁悬浮熔滴传递行为机理。使用Ar-C02作为氧化剂,电磁悬浮下Fe-Cr-C熔滴脱碳过程的反应限制环节为气相传质;在熔滴与石英管的直径比(dp/dc)=0.58-0.8,流体雷诺数范围Reh(4.09-132.16)的范围内,推导了脱碳过程中的传质系数舍伍德数,Sh的适用范围为26.86-82.14。
[Abstract]:The application of electromaglev in pyrometallurgical process can provide a non-contact melting environment for droplets, avoid crucible pollution to melt at high temperature, and provide good reaction kinetics conditions. The preparation of high quality metal and alloy products and the mechanism of metallurgical process were studied. The aim of this paper is to reveal the suspension behavior, oscillation behavior and transfer behavior of metal droplets under electromaglev. In order to ensure the accuracy of the model, the electromagnetic induction model and the multi-field coupling model combined with chemical process are established to predict the droplet behavior. The proposed model was verified by means of levitation force measurement experiment, electromaglev heating test and metal droplet transfer behavior experiment under the condition of electromaglev. The model was verified in a wide range of metals (copper, palladium, silver and aluminum). Using numerical model and dimensionless analysis method, the suspension and oscillation of droplet were studied in the range of gold. The decarburization process of Fe-Cr-C alloy under suspension was taken as an example. The transfer behavior of droplets was studied. The similar number of mass transfer in the decarbonization reaction is obtained. The main conclusions are as follows: 1) the effect of the environmental parameters of electromaglev on the droplet suspension behavior. The electromagnetic induction model is established. The environmental parameters affecting the droplet suspension behavior were established, including current angular frequency w, current intensity I, sample size D, and material properties 蟻 E. 渭. With the help of dimensionless analysis method, it is shown that the relationship between electromagnetic environment parameters and electromagnetic force F is in accordance with the formula: the formula can be combined with numerical simulation to predict the suspension conditions of droplets. The oscillatory behavior of the droplet in the melting process is explained. An approximate spring model of the electromaglev droplet is established, and copper, palladium, silver and aluminum are calculated. The oscillatory frequency of metal droplets of different materials in electromaglev melting process: in the current range 300-450A of the coil. The oscillation frequency of the droplet is between 10-30Hz and the oscillation behavior of the droplet is controlled accurately. It is helpful to expand the application of electromaglev technology. (3) taking copper droplet and Fe-Cr-C alloy droplet decarbonization as examples, the transfer behavior inside the droplet is studied, which is affected by electromagnetic stirring. The heat distribution in the droplet is more uniform, and the temperature difference between the copper droplet and the Fe-Cr-C alloy droplet is in the range of 1-4K. There is a strong eddy current in the droplet. The maximum velocities of copper droplet and Fe-Cr-C alloy droplet are 0.39 m / s and 0.272 m / s, respectively. The deformation ratio of the droplet increases, the eddy current inside the droplet develops continuously, and the effect of electromagnetic stirring is enhanced. The electromaglev droplet transfer mechanism was studied. Ar-C02 was used as oxidant. The reaction limitation of Fe-Cr-C droplet decarbonization under electromaglev is gas phase mass transfer. The ratio of the diameter of the droplet to the quartz tube is 0.58-0.8, and the Reynolds number of the fluid is 4.09-132.16). The suitable range of mass transfer coefficient Sherwood number Sh in the decarbonization process was deduced to be 26.86-82.14.
【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TF111.1

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