摘要
真空金属蒸气电弧作用下阴极表面热流密度和压力的不同时空分布情况,影响阴极表面蚀坑形成过程。结合阴极表面蚀坑形成过程中表面张力和马朗戈尼效应共同影响,建立考虑固、液、气态相变过程的二维轴对称流体动力学瞬态模型,描述阴极表面"火山口"形成的热力学行为,获得阴极最初喷射蒸气的表面结构和时间。阴极熔池相变过程中,熔融金属熔池中心形变和温度梯度较大,熔池流动由表面张力和马朗戈尼效应共同驱动,将熔坑中心热量转移至边缘,在蚀坑边缘,表面张力为熔池流动的主要驱动力。温度上升至临界温度,出现新的喷射爆炸点,"火山口"表面形成金属蒸气密度为10^25m^-3的覆盖层,密度分布与阴极蚀坑形状有关;增加热流密度、减小外部压力或增大作用半径,阴极表面覆盖层出现时间提前来到,蚀坑形状各异;当作用半径过小时,注入能量低,阴极斑点形成过程中蚀坑底部厚,半径小,蚀坑附近未产生金属蒸气覆盖层。
The formation process of surface crater is affected by the different time and space distribution of the thermal flux and pressure on the cathode in the action of vacuum metal vapor arc. After taking the influence of surface tension and Marangoni into account, a transient 2 D axially symmetric melting model has been developed to describe the thermodynamic behavior of molten metal on cathode surface and the formation of a crater. Moreover, the surface structure and initial time of metal vapor injection from the crater are obtained. In the process of metal phase transition, the deformation and temperature gradient in the center of molten metal pool are remarkable. Due to the Marangoni effect and the surface tension, the energy from the center of the molten metal on the cathode surface is transferred to the edge of the crater. At the edge of crater, the surface tension of the driving force is significant. As the temperature increases to the critical temperature, the new jet explosion point appears. The overburden layer of metal vapor density of 10^25 m^-3 on the surface of the crater is formed, in which distribution is related to the shape of the crater. By increasing the heat flux, reducing the external pressure and increasing the specified radius, the covering layer on the crater appears in advance. When the energy injected to the cathode is excessively low, the bottom of the crater is thick and the radius of the crater is small. Therefore, a dense metal vapor layer cannot be generated near the crater.
作者
付思
曹云东
李静
刘树鑫
韩颖
FU Si;CAO Yundong;LI Jing;LIU Shuxin;HAN Ying(Key Lab of Special Electric Machine and High Voltage Apparatus,Shenyang University of Technology,Shenyang 110870,China)
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2020年第3期843-851,共9页
High Voltage Engineering
基金
国家自然科学基金(51977132)
辽宁省自然科学基金(2019-MS-249)
辽宁省教育厅科学研究项目(LQGD2019010).
关键词
真空电弧
阴极
熔池
蚀坑
金属蒸气
vacuum arc
cathode
molten metal pool
crater
metal vapor
