长持续时间雷电流分量作用下电极形状对金属烧蚀特性的影响

采用试验与数值仿真相结合的方法分析了长持续时间的雷电流分量作用下电极形状对金属烧蚀特性的影响,对比了采用3种形状且不同头部曲率的电极时Al3003金属板的烧蚀面积和烧蚀深度,并结合有限元电场仿真和二维流注发展模型分析了电极影响金属烧蚀特性的原因.结果表明,电极对雷电流金属烧蚀特性的影响很大.在末次回击后长持续时间雷电流分量的作用下,使用尖电极造成的金属烧蚀面积和烧蚀深度最大,半椭球形电极和半球形电极造成的金属烧蚀面积和烧蚀深度次之,这是由于电极形状影响了间隙的初始电离能力以及流注发展过程中的电子密度分布和电子能量密度分布的缘故.

Metal Ablation Affected by Electrode Shapes Under Long Continuing Lightning Current

Adopting both experimental and simulation methods, this study mainly discusses the effect of electrode shapes on the metal ablation under lightning long continuing current component. In the experiment, the electrode is made of W80 material, and the test samples are aluminum 3003plates. The ablation areas and depths of the aluminum 3003 plates are compared under the tests with three types and three curvatures electrodes. Combining the finite element electric field simulation and 2 dimensional streamer development model analysis, the mechanism of the electrode’s impact on the metal ablation property is also discussed. The results show that the effect of electrode’s shape cannot be ignored in metal ablation experiments. Under the lightning long continuing current component after the last return stroke, cone electrode leads to the severest ablation both in ablation area and depth, whilst the hemisphere electrode leads to the lightest ablation. Moreover, electrode shape also affects the capability of initial ionization within the gap. The electron density and electron energy density distribution during the process of streamer development dominates the impact of electrodes on the metal ablation.