30 / 2021-05-24 22:29:10

甲烷/空气混合气体在针板电极下的微间隙放电特性研究

摘要：目前爆炸性气体在微间隙下的放电特性尚不明晰，且大多从宏观角度进行研究，缺少微观层面的理论分析，对此本文基于IEC火花试验装置采用流体动力学方法模拟研究了甲烷—空气混合气体在电压为24V，极板间距为6μm下的微间隙放电微观动力学过程。通过分析极间距、甲烷气体浓度等宏观变化对电子密度、各正离子数密度、电场强度和平均电子能量的影响，从离子微观角度阐明了微间隙放电机理。结果表明：极板间距为6μm时，微间隙气体放电过程中离子碰撞电离占主导地位，且在放电过程中，电子密度随时间呈先增长后下降最后达到稳定的趋势；随着极板间距减小，电场强度会增大，从而导致了离子碰撞电离反应速率加快，平均电子能量增加；甲烷浓度在3.5%~13.5%范围变化时，会影响碰撞电离产生的CH₄⁺数密度，但从N₂⁺数密度、平均电子能量及电子温度角度分析，其浓度变化对整体微间隙放电影响很小。



关键词：火花试验装置；流体动力学方法；微间隙放电；离子碰撞电离；



Abstract: At present, the discharge characteristics of explosive gas in micro gap are still unclear, and most of them are studied from the macroscopic view, lacking the theoretical analysis in microscopic view. To address this concern, the kinetics process of the micro-gap discharge in the methane-air mixture with a voltage between parallel plates of 24 V and a pole pitch of 6 μm are studied and simulated by utilizing the fluid dynamics method based on the IEC spark test device. Besides, the Mechanism of microgap discharge is clarified from the ion microscopic view by analyzing the influence of macro changes such as electrode spacing and methane gas concentration on electron density, positive ion number density, electric field strength and average electron energy. The results show that when the pole distance is 6 μm, the ion collision electricity is dominated during the micro-gap gas discharge process, and the electron density increases initially and decreases afterwards with time, finally reaches a stable trend. The electric field strength increases with the decrease of electrode plate interval, resulting in the acceleration of ion collision ionization reaction and the increase of average electron energy. When the methane concentration changes in the range of 3.5% to 13.5%, it will affect the CH4 + digital density generated by the collision ionization, however, the change of its concentration has little effect on the whole microgap discharge through analyzing from the view of N2 + digital density, average electron energy and electron temperature.



Key words: Spark test device; Fluid dynamics method; Micro gap discharge; Ion collision ionization；