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为研究等离子体强化甲烷点火的动力学机理,把等离子体强化点火过程简化为放电和点火两个阶段分别进行分析。在放电阶段,采用零维等离子体动力学模型,分析了活性粒子摩尔分数的演化规律和约化场强对粒子摩尔分数的影响;在点火阶段,采用零维均质点火模型,研究了自由基摩尔分数的演化规律以及沉积能量和约化场强对点火延迟时间的影响。结果表明,高能电子与中性粒子发生碰撞等系列反应最终生成若干自由基,完成高能电子中的能量到自由基键能的转移,O自由基的摩尔分数最大;等离子体强化点火条件下CH3的氧化路径由自点火的R155 CH3+O2=O+CH3O、R156 CH3+O2=OH+CH2O改成R10 O+CH3=CH2O+H和R284 O+CH3=H+H2+CO,自由基摩尔分数和反应速率增加约3个量级,点火延迟时间缩短约1个量级,自由基键能最终转化为内能。
In order to study the kinetic mechanism of plasma-enhanced methane ignition, the plasma-enhanced ignition process is simplified to two stages of discharge and ignition respectively for analysis. In the discharge phase, the zero-dimensional plasma dynamics model was used to analyze the evolution of the mole fraction of activated particles and the effect of the reduced field strength on the mole fraction of the particles. In the ignition phase, The evolution of fraction and the influence of deposition energy and reduced field strength on ignition delay time. The results show that a series of reactions such as collisions between energetic electrons and neutral particles eventually generate several free radicals and complete the transfer of energy to free radical bond energies in high-energy electrons with the largest molar fraction of O radicals. In the case of plasma-enhanced ignition, CH3 The oxidation path was changed from self-igniting R155 CH3 + O2 = O + CH3O, R156 CH3 + O2 = OH + CH2O to R10 O + CH3 = CH2O + H and R284 O + CH3 = H + H2 + The reaction rate increases about 3 orders of magnitude, and the ignition delay time is shortened by about one order of magnitude. The radical bond energy can eventually be converted into internal energy.