Unclean air discharge refers to the discharge phenomenon of a large number of polluting gases, droplets or solid particles floating in the air, which will cause insulation breakdown and safety accidents for the power transmission equipment that have been left outdoors for a long time. In order to investigate the effects of particle concentration, particle size and dielectric constant on DC breakdown characteristics of unclean air gap, a self-made discharge chamber was designed in this study. The air was filtered and passed into the discharge chamber to remove the influence of impurities contained in the air on the experimental results. Then, solid particles with different concentration, particle size and particle dielectric constant were added to the discharge chamber to carry out the DC positive polarity breakdown characteristic experiment. The experimental results show that compared with dry clean air, the presence of solid particle increases the breakdown voltage of the gap, and the increase proportion of breakdown voltage is related to the particle concentration, particle size and particle dielectric constant. With the same particle type and particle size, the increase proportion of breakdown voltage increases with the higher concentration, which up to 10.49%. For further investigating, the fluid mechanics model was selected to simulate the process of streamer discharge in unclean air. The results show that compared with dry clean air, the presence of particles enhances the gap discharge ionisation process, but also enhances the adsorption of particles, and the latter has stronger effect than the former, thus increases the gap breakdown voltage. At the same time, the enhancement of adsorption effect increases the electric field intensity of the gap and speeds up the development process of streamer discharge.

中文翻译：

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固体颗粒类型、浓度和尺寸对短针板气隙直流击穿电压的影响：实验与模拟研究

不洁空气放电是指空气中飘浮着大量污染性气体、液滴或固体颗粒的放电现象，会对长期搁置在室外的输电设备造成绝缘击穿和安全事故。为了研究颗粒浓度、颗粒尺寸和介电常数对不洁净气隙直流击穿特性的影响，本研究设计了自制的放电室。空气经过滤后通入放电室，去除空气中所含杂质对实验结果的影响。然后将不同浓度、粒径和颗粒介电常数的固体颗粒添加到放电室中，进行直流正极性击穿特性实验。实验结果表明，与干燥清洁空气相比，固体颗粒的存在使间隙的击穿电压增加，击穿电压增加的比例与颗粒浓度、颗粒尺寸和颗粒介电常数有关。在相同的颗粒类型和粒径下，击穿电压的增加比例随着浓度的增加而增加，最高可达10.49%。为了进一步研究，选择流体力学模型来模拟不洁净空气中流光放电的过程。结果表明，与干燥清洁空气相比，颗粒物的存在增强了间隙放电电离过程，同时也增强了颗粒物的吸附，且后者的作用强于前者，从而提高了间隙击穿电压。同时，