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首页> 外文期刊>Journal of Physics, D. Applied Physics: A Europhysics Journal >Numerical analysis of fume formation mechanism in arc welding
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Numerical analysis of fume formation mechanism in arc welding

机译：电弧焊烟气形成机理的数值分析

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In order to clarify the fume formation mechanism in arc welding, a quantitative investigation based on the knowledge of interaction among the electrode, arc and weld pool is indispensable. A fume formation model consisting of a heterogeneous condensation model, a homogeneous nucleation model and a coagulation model has been developed and coupled with the GTA or GMA welding model. A series of processes from evaporation of metal vapour to fume formation from the metal vapour was totally investigated by employing this simulation model. The aim of this paper is to visualize the fume formation process and clarify the fume formation mechanism theoretically through a numerical analysis. Furthermore, the reliability of the simulation model was also evaluated through a comparison of the simulation result with the experimental result. As a result, it was found that the size of the secondary particles consisting of small particles with a size of several tens of nanometres reached 300 nm at maximum and the secondary particle was in a U-shaped chain form in helium GTA welding. Furthermore, it was also clarified that most part of the fume was produced in the downstream region of the arc originating from the metal vapour evaporated mainly from the droplet in argon GMA welding. The fume was constituted by particles with a size of several tens of nanometres and had similar characteristics to that of GTA welding. On the other hand, if the metal transfer becomes unstable and the metal vapour near the droplet diffuses directly towards the surroundings of the arc not getting into the plasma flow, the size of the particles reaches several hundred nanometres.
机译：为了阐明电弧焊中烟气的形成机理，基于焊条，电弧和焊缝之间相互作用的知识进行定量研究是必不可少的。已经开发了由异质冷凝模型，均相成核模型和凝结模型组成的烟气形成模型，并将其与GTA或GMA焊接模型相结合。通过使用该仿真模型，对从金属蒸气蒸发到从金属蒸气形成烟雾的一系列过程进行了全面研究。本文的目的是可视化烟雾形成过程，并通过数值分析从理论上阐明烟雾形成机理。此外，还通过将仿真结果与实验结果进行比较来评估仿真模型的可靠性。结果，发现由几十纳米大小的小颗粒组成的次级颗粒的尺寸最大达到300nm，并且在氦气GTA焊接中次级颗粒呈U形链形式。此外，还澄清了烟气的大部分是在电弧的下游区域产生的，该气体的下游区域的气体主要是在氩气GMA焊接中从液滴中蒸发出来的金属蒸气所致。烟尘由几十纳米大小的颗粒组成，具有与GTA焊接相似的特性。另一方面，如果金属转移变得不稳定，并且液滴附近的金属蒸气直接向电弧周围扩散而不进入等离子流，则粒子的尺寸将达到数百纳米。

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