【作者】 茄菊红；

【导师】 徐达鸣；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2007， 硕士

【摘要】 在钢锭连铸过程中,合金熔体的传热、传质和熔体流动是凝固过程中重要的传输现象,这些传输行为决定着铸锭的结晶质量。同时凝固过程各个传输现象之间彼此紧密关联并相互影响,加入电磁场后会使这种耦合传输现象更加复杂。因此,研究电磁连铸凝固过程中耦合传输现象,揭示电磁场作用下钢凝固传输行为的规律,可为优化工艺参数提高铸件质量提供依据,具有重要的研究意义。本文以理论建模和计算机模拟为研究手段,基于本课题组已有的研究工作,将凝固传热、传质及动量传输的耦合传输统一模型应用到电磁连铸过程,以实现钢锭连铸系统电磁场和凝固传输的耦合传输数值模拟。为此,本论文进行了如下研究工作:建立了在电磁场与重力场共同作用下,连铸钢锭相对实验室静止坐标系以一定的抽拉速度V0运动的电磁凝固过程传热、传质与动量传输的耦合数学模型与数值计算方法。采用FORTRAN语言编制了电磁连铸的凝固传输计算程序,实现了电磁连铸凝固传输的耦合数值模拟。采用ANSYS软件分析计算了本论文钢锭电磁连铸过程所施加的电磁场,包括不同强度的横向静磁场和不同形式的行波电磁场。利用本试验室自行研发的FORTRAN有限元/有限差数据格式转换技术,将ANSYS计算的基于有限元分析的电磁场的计算结果转换为凝固传输计算程序可读的有限差格式的数据。将电磁场计算结果耦合到连铸凝固传输计算程序中,初步实现了钢锭连铸凝固传输与电磁场的耦合数值模拟。模拟结果包括:液相流场、固相分数场、洛仑兹力场、温度场和成分场等。进行了无磁场仅重力场作用下钢锭连铸凝固传输的数值计算,表明本文所建立的相对静止坐标系运动条件下电磁连铸系统凝固传输耦合模型及数值计算方法是可行的。进行了初步的静磁场/行波电磁场和重力场共同作用下的连铸钢锭凝固传输行为的耦合数值模拟计算,分析了不同强度的磁场对液相流场的抑制作用,考察了不同极对数的行波电磁场对连铸钢锭凝固过程的影响。更多还原

【Abstract】 The solidification transport phenomena (STP), i.e. heat, mass and momentum transfer in alloy solidification systems are very important and complicated due to the strong coupling among them. When an electromagnetic filed (EMF) is applied to the solidifying system, that coupled correlations will becom even more complicated. Research on the coupled solidification transport phenomena and the influence of EMF on the solidified process of steel ingot can give advice to improve the quality of ingots, and is very meaningful.The aim of the present thesis is to establish an EM-coupled continuum model for STP in the electromagnetic continuous casting (CC) processes of steel ingots based on the previous work of our research group, using the method of theoretical modeling and computer simulation. The main work inclued:The mathematical model in a continuum form and the corresponding numerical formula for the electromagnetic STP of the steel ingot in EMC process are established, which is under both gravity and electromagnetic fields and with a movement velocity V0 relatively to the static lab coordinate. Computer codes in FORTRAN language is developed for numerical simulation of the EMC-STP processes.The ANSYS software is explored to analyze the static and traveling magnetic fileds applied to the EMC system. Conversion of the EMF-data from ANSYS finite element method (FEM) format, included the B vector field, induction current density, Joule heat and so on, to finite different method (FDM) format is performed using our own data processing FORTRAN program.Coupling the conversed EMF-data to the STP simulation program, preliminary computational results, including the liquid flow velocity, temperature filed, solid volume fraction filed, Lorentz force filed and so on in EM-continuous casting processes of steel ingots, indicate that the present computer modeling is successful.The coupled simulation results for the CC-STP behaviors under different static and traveling EMFs show that, application of a static magnetic field to the steel ingot continuous casting process can effectively suppress the bulk liquid flow, and the braking effects enhance with the increase of the magnetic field’s intensity; the application of traveling magnetic field can obviously change the liquid flow patterns.更多还原