外场辅助下焊接热源特性数值分析
Numerical Simulation of Welding Arc with the Assist of External Magnetic Field

窄间隙钨极氩弧焊工艺是厚板构件焊接的重要技术之一，该工艺的关键是保证焊接电弧热量在坡口表面合理分布。本文基于Ansys Fluent建立了外部磁场辅助下窄间隙钨极氩弧焊工艺的三维数值分析模型，研究外部磁场与窄间隙双重作用下，钨极氩弧焊电弧的热量分布特征。研究结果表明，窄间隙侧壁约束了焊接电弧在横向上的自由扩展，使焊接电弧失去轴对称特性，焊接电弧高温区域变为纵向长、横向短的椭圆形。外部施加的磁场使焊接电弧等离子体偏离原来运动轨道、偏向窄间隙侧壁。从而焊接电弧直接作用于侧壁，增大侧壁热输入，避免侧壁融合不良现象的发生。
Narrow gap gas tungsten arc welding (NG-GTAW) is one of the important joining technologies for thick plate components. The key of the process is the reasonable distribution of the arc on the groove surface. A three dimensional simulation model was developed for the external magnetic assisted NG-GTAW by Ansys Fluent to investigate the distribution characteristics of plasma arc heat flux under the influences of the groove geometry and the external magnetic field. The simulation results show that the transverse expansion of plasma arc is constrained by the groove sidewalls which results the arc is no longer asymmetry. Its high temperature region changes to ellipse. The plasma arc deviates from its original course and towards to one sidewall of the groove under the influence of external magnetic field. So the plasma arc can make direct contribution to the sidewall and increasing its heat flux and avoiding the appearance of bad fusion.