废气组分对天然气非平衡等离子体点火助燃的影响机制

Non-equilibrium plasma ignition has a potential to extend lean burn limit, improve operation stability, fuel economy and emission performance of internal combustion engine. Therefore, non-equilibrium plasma ignition technology has important application value in energy and power field. However, the researches of non-equilibrium plasma ignition and assisted combustion mainly adopt a method to ionize fuel or air, the influence of exhaust gas components on ionization and active particle generation are hardly considered by researchers at the present stage. For internal combustion engine, exhaust gas accompanies with the whole process of ignition and combustion, the influence of incomplete oxidation products and non-combustible components in the exhaust gas on ionization and reaction processes could not be ignored. It is necessary to carry out systematic research. .This research focuses on natural gas discharge, active particles generation, and the reaction mechanism between waste gas component molecules and active particles, to carry out a research of influence mechanism of exhaust gas components on natural gas non-equilibrium plasma ignition. Theoretical analysis, laboratory test and numerical simulation would be employed to found a reaction mechanism based on detailed chemical reaction kinetics of exhaust gas molecules and activated particles generated by natural gas discharge and to construct computing model, elucidate the influence law of exhaust gas components on combustion characteristics of natural gas non-equilibrium plasma ignition, and finally to provide the basis for the theoretical research and technological progress of non-equilibrium plasma ignition.

非平衡等离子体点火具有拓宽稀燃极限、改善发动机燃烧稳定性、燃油经济性及排放性能的巨大潜力，在能源动力领域具有重要应用价值。然而，目前天然气等离子体点火、助燃研究多采用电离燃料或空气的方式，并未考虑燃烧废气组分对电离及活性粒子生成过程的影响作用；而对内燃机而言，燃烧废气一直伴随点火及燃烧的整个过程，废气中的不完全氧化产物及非可燃组分对电离及反应过程的影响作用不容忽视，需要进行深入系统的研究。本课题以天然气放电及活性粒子生成、废气组分分子与活性粒子的相互作用机制为研究对象，进行废气组分对天然气非平衡等离子体点火助燃影响机制研究，采用理论分析、试验室试验及数值模拟相结合的研究手段，建立基于详细化学反应动力学的废气组分气体分子与天然气放电活性粒子之间的作用机制并构建计算模型，阐明废气组分对天然气非平衡等离子体点火助燃的着火及燃烧特性的影响规律，为非平衡等离子体点火技术的理论研究及技术进步提供依据。

本课题提出了基于双模式放电思想的多种等离子体点火器结构，针对二冲程发动机结构特点，提出了与之匹配的等离子体点火电极及点火器结构，以及非平衡等离子体助燃激励器的控制策略。提出了应用于机理文件编写的化学反应速率系数的求解方法，构建了非平衡等离子体电离及燃烧反应机理。采用自主设计的射流反应器，针对甲烷、氩气、氮气、空气等不同电离介质的非平衡等离子体射流特性，研究了射流反应器的电极结构对射流及电离特性的影响规律。进行了非平衡等离子体气体放电的数值模拟研究，建立了基于同轴电极介质阻挡放电的非平衡等离子体的电离特性及控制策略。采用自主研发的非平衡等离子体点火器，进行了天然气非平衡等离子体低温点火的燃烧特性的初步研究，明确了等离子体对天然气燃烧特性的影响规律。