大面积分散电弧等离子体发生器中传热与流动的实验和数值模拟研究

项目名称： 大面积分散电弧等离子体发生器中传热与流动的实验和数值模拟研究

项目编号： No.50876101

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 建筑科学

项目作者： 夏维东

作者单位： 中国科学技术大学

项目金额： 40万元

中文摘要： 磁分散电弧是一种新颖的大尺度电弧热等离子体产生方式。采用数值模拟和实验方法研究了磁分散电弧等离子体的流动与传热，包括电极形状、发生器结构参数、外部条件等对磁分散电弧等离子体影响。数值模拟计算中，改进了Lowke阴极模型，编写了相应的Fluent的UDF程序，计算域包含了阴极。研究表明磁分散电弧等离子体具有扩散型阴极弧根和阳极弧根以及分散均匀的大尺度等离子体；扩散型阴极弧根的位置和形状受电极形状、外部参数影响，也反过来影响等离子体位形；数值模拟结果表明，在大尺度磁分散电弧等离子体发生器中，扩散型阴极弧根的电流密度低于10A/mm2、阳极电流密度低于0.2A/mm2，分别低于轴向射流电弧等离子体电极电流密度1个数量级。另一个成果是双温等离子体输运性质的初步研究：基于简化Boltzmann方程，利用改进的Chapman-Enskog方法，推导出一组简化的双温等离子体输运性质计算公式和控制方程表达式。基本控制方程和相应计算条件下等离子体输运性质的表达式是完全自洽的。公式包括了附加的温度比梯度项，在LTE条件下可以回复到有关热平衡等离子体数值模拟的控制方程和输运性质计算公式，满足粒子通量守恒。

中文关键词： 磁分散电弧；扩散阴极弧根；传热与流动；双温等离子体；输运性质

英文摘要： Magnetically Dispersed Arc Plasma is a novel large scale arc plasma source. In this work, the heat transfer and flow of magnetically dispersed arc plasma are numerically and experimentally researched, including the effection of the shape of the cathode, the configration and size of the generator, technic conditions (arc currents, axial magnetism, Ar flow), and etc. A model about the cathode by J J Lowke is modified to satisfy the Fluent and the corresponding UDF Code is written, so as that the cathde could be fit into the calculation domain. The reaserch results show that diffussion arc root attached on the the cathode and on the anode, as well as homogeneously large scale dispersed arc plasma are in the LADAPS (Large Area Dispersed Arc Plasma Source). The current density on the cathdoe and the anode are respectively less than 107A/m2 and 2*105A/m2, those are lower an order of magnitude than those in the axial jet arc plasma generator. In this work, a new set of simplified formulas for the transport properties of 2-T plasmas and a set of controlled equations are obtained based on the solution of the simplified Boltzmann equation using a modified Chapman-Enskog method. These formulas include additional terms in the gradient of the temperature ratio ? (=Te/Th, where Te and Th respectively represent the temperature of electrons and heavy particles), can be reduced to their counterparts for the LTE plasmas with Te=Th=T, and satisfy the requirement that the diffusion flux is conserved in the plasma system.

英文关键词： Magnetically dispersed arc plasma；Diffusion arc root；Heat transfer and flow；Two-temperature plasma；Transport properties