排水罩风场特征及其对焊接电弧影响的数值模拟

水下焊接技术在水下工程建设和修复方面具有大量的应用需求. 在水下焊接方法中，局部干法焊接采用排水罩将焊接区域的水排开进行焊接，接头质量较好，易于实现水下自动化焊接. 然而，局部干法焊接时需要在排水罩内通入高压空气将水排开. 为了研究高压气体在排水罩内形成的风场结构及其对焊接过程和电弧特性的影响，文中采用数值模拟的方法，对排水罩内的湍流气体进行了模拟. 并研究了排水罩内侧向风场对电弧等离子体的温度场、速度场、压力场的影响规律. 发现侧向风场对弧柱中心区以外部分的影响较大，弧柱的吹偏角度与侧向风速基本上呈线性关系. 最后进行了焊接试验，采用高速相机拍摄电弧在不同侧向风速下的形态，发现其实际变化与模拟结果基本一致.

Numerical simulation of wind characteristics in local dry welding chamber and its influence on welding arc

Underwater welding technology has been widely applied in the building and repairing of underwater construction in recent years. In the underwater welding technologies, local dry welding method which adopts local dry chamber to prevent the effect of water on the welding process has some advantageous such as better joint quality and ease to realize automatic welding. However, in the process of local dry welding the high pressure compress air need to be injected into the local dry chamber in order to prevent the water flow into it. In this paper, a numerical simulation method is adopted to study the structure of the wind field in the local dry chamber firstly. Based on the simulation results, the structure of local dry chamber is optimized. And then the impacts of the wind field in the local chamber to the welding process and arc characteristics such as the arc temperatures, velocities and pressures are analyzed. The simulation results show that the lateral wind has a great influence on the welding arc column, and the declination of arc column displays a linear relationship with the increasing of lateral wind speed. Finally, a high speed camera is used in the welding experiments to photograph the arc shape under different lateral wind. It is found that the experimental results are consistent with the simulation results.