交流放电等离子体助燃乙烯/空气的数值模拟  

Numerical Simulation of AC Discharge Plasma Assisted Ethylene/Air Combustion

作　　者：班杨杨 张帆[1] 钟生辉 朱家健[2] Yangyang;ZHANG Fan;ZHONG Shenghui;ZHU Jiajian(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China;Science and Technology on Scramjet Laboratory,National University of Defense Technology,Changsha 410073,China)

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072 [2]国防科学技术大学高超声速冲压发动机技术重点实验室,长沙410073

出　　处：《内燃机工程》2022年第1期58-66,共9页Chinese Internal Combustion Engine Engineering

基　　金：国家自然科学基金项目(51876139,51606217);湖南创新型省份建设专项经费项目(2019RS2028)。

摘　　要：通过耦合零维等离子动力学求解器和燃烧动力学求解器,建立了交流放电等离子体助燃模型,研究了交流放电非平衡等离子体对C_(2)H_(4)/空气的助燃路径,并与自燃过程进行了对比。该模型使用电子能量分布函数计算电子碰撞反应速率,并得到贫燃条件下连续放电过程中温度、组分浓度、放热速率、关键组分的生成/消耗速率随时间的变化。研究表明,等离子体助燃增加了新的反应路径,生成了更多的自由基和激发态组分,缩短滞燃期近两个数量级。氧气、氮气激发态的弛豫和淬熄过程促使电能—化学能—热能的转化,放电结束后的总放热量增加,最高燃烧温度比自燃条件下高约400 K。同时,电子碰撞O_(2)、N_(2)激发态与O_(2)的退激反应、单态氧原子O(1D)的弛豫等过程促进了氧原子的生成。此外,H原子的生成间接提高了O原子的物质的量分数(主要通过H+O_(2)→OH+O),加速C_(2)H_(4)氧化生成HCO、CO等,缩短了点火延迟时间,有助于燃烧效率的提高。The plasma assisted combustion model was established by coupling zero-dimensional plasma kinetic solver and combustion kinetic solver to study the effect of non-equilibrium plasma by AC discharge on the combustion process of C_(2)H_(4)/air mixture and compared with auto-ignition process.In this model,the electron energy distribution function was solved for electron collision reaction rates and the temporal evolution of temperature,species concentration,heat release rates and production/consumption rates of the key species were obtained during continuous discharge under lean-burn condition.The results show that under the condition of plasma assisted combustion,new reaction pathways,more radicals and excited components are produced,and the ignition delay time is shortened by nearly two orders of magnitude.With plasma,the quenching and relaxation of the excited oxygen and nitrogen molecules lead to the conversion from electric energy,chemical energy to heat energy.Thus,the total heat release after discharging increases and the maximal combustion temperature is around 400 K higher.In addition,the collisions between electron and O_(2),the de-excitation reaction of N_(2)excited states and the singlet oxygen O(1D)promote the formation of oxygen atom.Also,the formation of H atom increases O atom mainly through reaction H+O_(2)→OH+O,accelerating the oxidation of C_(2)H_(4) to HCO and CO as well as the shorter ignition delay time and the higher combustion efficiency.

关 键 词：非平衡等离子助燃 交流放电 乙烯 数值仿真 

分 类 号：TK432[动力工程及工程热物理—动力机械及工程]