直流电弧等离子炬温度场-电场分布特性数值模拟  

Numerical Simulation of the Temperature-electrical Field Characteristics in DC Arc Plasma Torches

作　　者：黄卫星[1] 武劭恂 司徒达志 张子炜 李晴 HUANG Weixing;WU Shaoxun;SITU Dazhi;ZHANG Ziwei;LI Qing(School of Chemical Eng.,Sichuan Univ.,Chengdu 610065,China;China Nuclear Power Technol.Research Inst.Co.Ltd.,China General Nuclear Power Group,Shenzhen 518124,China)

机构地区：[1]四川大学化学工程学院,四川成都610065 [2]中国广核集团中广核研究院有限公司,广东深圳518124

出　　处：《工程科学与技术》2020年第5期236-241,共6页Advanced Engineering Sciences

摘　　要：由于热等离子体技术能源利用率高、工艺清洁且效果良好,在固体废弃物焚烧处理中已成为热点开发技术,其中,直流电弧等离子体是近年来放射性固废处理领域的重点研究技术。工业用等离子炬作为实现这一技术的核心装置,其内部温度极高、温度场与电磁场耦合,且实验测试困难,因此发生装置的开发和优化设计必须借助数值模拟手段。以直流非转移弧等离子炬为对象,基于Fluent软件用户自定义函数(user-defined function,UDF)与用户自定义标量(user-defined scalar,UDS)的二次开发功能,通过分析热等离子体的热力学特性,将数值模拟过程与工质气的物性参数(热力学系数、输运系数)、控制方程组源项变化及电极电流分布进行动态链接,建立了2维轴对称的磁流体动力学(magnetohydrodynamics,MHD)计算模型;并采用合理的边界条件,通过求解流体力学控制方程组与麦克斯韦方程组,得到了等离子炬内特征物理参数的分布规律。结果显示:阴极附近电位降显著,电流密度分布集中;层流条件下弧柱区温度分布均匀,中心温度为全流域最高,区域边缘温度梯度较大;阳极附近存在电流密集分布区域,可作为弧根位置预测依据。针对电弧在电极表面的附着现象,后续可继续进行电极-等离子体的耦合模型计算,以得到设备内壁面更加准确的温度分布。Due to the high utilization rate,clean process and good effect of thermal plasma technology,it has become a hot development technology in solid waste incinerations.Among them,DC arc plasma is a key research technology in the field of radioactive solid waste treatment in recent years.The industrial plasma torch is the core device to realize this technology.But the internal temperature is extremely high,the temperature field and the electromagnetic field are coupled,and the experimental test is difficult.Therefore,the development and optimization of the device must rely on numerical simulation.Based on the secondary development functions of user-defined function and user-defined scalar and by analyzing the thermodynamic characteristics of the thermal plasma,the numerical simulation process was dynamically linked to the physical property parameters of the working gas,the source terms of the control equations and the electrode current distribution,thereby establishing two-dimensional axisymmetric Magnetohydrodynamics model.And using reasonable boundary conditions,the distribution law of characteristic physical parameters in the plasma torch was obtained by solving the hydromechanical control equations and Maxwell equations.The results showed that the potential drop was significant and the current density distribution was concentrated near the cathode;under laminar flow conditions,the temperature distribution in the arc column area was uniform,the center temperature was the highest in the entire basin,and the temperature gradient at the edge of the area was large;there was a dense current distribution area near the anode,which could be used as the basis for arc root position prediction.In view of the adhesion of the arc on the electrode surface,the electrode-plasma-coupling model can be calculated to obtain a more accurate temperature distribution on the inner wall surface of the device.

关 键 词：等离子炬 直流非转移弧 固废处理 数值模拟 Fluent二次开发 

分 类 号：X705[环境科学与工程—环境工程]