孤立金属尖端的电晕触发阈值  

Onset Corona Field Based on Isolated Metal Tip

作　　者：谭涌波[1,2] 朱俊儒[1,2] 李祥超[1,2] 梁忠武 郭秀峰[1,2] 

机构地区：[1]南京信息工程大学气象灾害预报预警与评估协同创新中心,南京210044 [2]南京信息工程大学中国气象局气溶胶与云降水重点开放实验室,南京210044

出　　处：《应用气象学报》2014年第3期339-346,共8页Journal of Applied Meteorological Science

基　　金：国家自然科学基金项目(41175003;41075003)

摘　　要：为了得到金属尖端在发生电晕放电时尖端处的电场强度,该文首先采用实验室实验得到不同高度、不同形状、不同材质的金属尖端发生电晕放电时的环境电场阈值;再采用有限元法计算二维泊松方程,得到尖端处电晕触发阈值,由此得出以下结论:环境电场阈值随金属尖端高度的增大基本呈线性减小趋势,随着尖端越来越尖,环境电场阈值呈先减小后增大的变化趋势;高度、形状对金属物尖端处电晕触发阈值无影响,尖端处电晕阈值为定值;给出尖端处电晕触发阈值为158.75 kV·m^(-1)与空间分辨率的拟合公式,可为今后电晕放电数值模拟中判断电晕放电的起始时刻提供参考。Corona discharges characterized by much lower current densities are often generated in a strong atmos pheric electric field. What＇s more, corona discharges are very important because the corona charge layers can change the distribution of the electric field near the ground and affect conditions of the initiation and development of an upward leader near different tall objects. Therefore, corona discharges have attracted the attention of scholars at home and abroad, especially in the onset corona field. However, how to effectively show corona emission threshold is still a difficult problem in the study of atmospheric electricity. In order to obtain the electric field strength at the tip of metal in the case of corona discharge, the onset corona voltages must be obtained by laboratory test for different heights, shapes and materials of metal tips which are arranged on the middle of lower plate of two parallel metal plates. Dimensions of two horizontal plates are 1.2 m by 1.2 m and the distance between them is 1 m. Then environmental threshold e lectric fields are calculated for different heights, shapes and materials of metal tips. The two-dimensional Poisson equation is solved using finite element method and the corona emission thresholds at the tip of different types of metal tips are obtained. Effects on threshold electric fields by the height, material and shape are discussed, respectively. The following conclusions can be drawn from the experimental study. First, the environmental threshold fields are basically a linear decrease with heights of metal. The environmental threshold fields decrease first and then increase when metal tips are becoming sharp increasingly. Second, the height and shape of mental tips have no effects on corona emission threshold at the tip of metal tips. The corona threshold at the tip of mental tip is a constant. Finally, the corona triggering threshold is determined which is Ec = 158.75 kV·m^-1 and the fitting function between corona emission threshold and spatial resolution is

关 键 词：电晕放电 实验室模拟 电晕触发阈值 有限元 空间分辨率 

分 类 号：TM83[电气工程—高电压与绝缘技术]