| 摘要: |
| 基于局域热力学平衡假设，建立三维非稳态的磁流体动力学模型，在给定气流量和工作电流的条件下，采用数值模拟方法研究不同注气方式对直流非转移弧等离子喷枪内ArH2等离子电弧的波动行为和等离子特性的影响。结果表明，与直流进气相比较，采用旋转方式进气时，喷枪内等离子体流的流线呈现出明显的螺旋状分布，电弧波动信号呈现出更高的平均电压和较高波动频率,电弧附着随时间变化呈现出圆周运动现象；喷枪内等离子体的最大温度出现在阴极尖端附近,采用旋转方式注气时等离子平均最大温度较低，而等离子体的速度沿中心轴方向呈现出先增加后减小的趋势。喷枪出口处等离子体的温度与速度同样显示出波动分布，两种进气方式得到的温度分布基本相似，采用旋转方式注气时等离子平均最大速度分布相对较高。 |
| 关键词: 等离子喷枪 磁流体力学 数值模拟 注气方式 |
| DOI：10.3969/j.issn.1007-9289.2014.02.003 |
| 分类号: |
| 基金项目: |
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| Influence of Gas Injection Methods on the Electric Arc Instability of a Plasma Torch |
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CAO Pingli, ZHENG Yunzhai, ZHENG Zhenhuan, LI Qiang
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School of Materials Science and Engineering, Fuzhou University, Fuzhou 350108
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| Abstract: |
| A threedimensional transient local thermodynamic equilibrium (LTE) magnetohydrodynamic model of the nontransfer D.C. plasma torch was presented. A numerical modeling method was used to investigate the influence of gas injection methods on the ArH2 electric arc instabilities and plasma characteristic under certain gas flow and electric current. The results show that the streamlines of the plasma present a spiral distribution and the arc has a higher mean voltage and frequencies of voltage signal when operated with swirl flow. The arc attachment can also be observed with a small circumferential movement. The maximum plasma temperature inside the torch appears around the cathode tip, and the plasma velocity distribution presents a trend of first increases and then decreases along the central axis. Compared with straight flow, the arc operated with swirl flow has a lower average maximum temperature. The plasma temperature and velocity at the torch exit also experience significant fluctuation with the arc root movement and transition. The plasma temperature distribution at the torch exit with the two ways is similar, while the arc operated with swirl flow has a lower average maximum velocity. |
| Key words: plasma torch magneto hydrodynamic numerical simulation gas injection methods |
