水深和流速对水下湿法焊接热过程影响的数值模拟

Numerical simulation of influence of water depth and flowing speed on thermal process of underwater wet welding

水下电弧在高压和强烈冷却作用的环境下,其弧压、形态和能量密度都发生了改变,工件的换热条件更发生了显著的变化.文中考虑水下压力对电弧的压缩和水环境中工件换热速度的提高,进行一定的参数假设,建立了湿法熔化极气体保护焊接热过程的数值分析模型,得出了不同水深和不同水流速度下的工件热循环曲线、熔池形状等典型数据.模拟结果表明,随水深增加,熔池的深度增加而宽度减小,各等温线的形状也逐步变得狭窄而且更深;随工件表面水流速度增大,熔池变小,等温面所笼罩的体积也显著减小.

The pressure,shape and thermal density of a welding arc will change under high-pressure and strong-cooling underwater environment,so will the heat exchange on the workpiece surface.In this paper,a FEM model of the thermal process of underwater wet gas metal arc welding was established using SYSWELD.Two remarkable characteristics of underwater wet welding-the water compressing action on the arc and the enhanced heat loss caused by the surrounding water-were considered in the model by adjusting the heat sources and convection coefficient on the workpiece surface.Then thermal cycles and weld pool profiles under different water depths and different water flowing speeds were obtained.The calculated results show that the weld pool became deeper and narrower in deeper water,and so did the profiles of the isotherms.And the results also revealed that the weld pool and profiles of isotherms became narrower and shallower when the water flowing speed increased.