发动机稀燃条件下纳秒脉冲等离子体助燃甲烷/空气的数值模拟  

Nanosecond Pulsed Plasma Assisted Ignition of Methane/Air Under Lean-Burn Conditions of Engines

作　　者：班杨杨 张帆[1] 钟生辉 朱家健 Ban 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]国防科技大学高超声速冲压发动机技术重点实验室,长沙410073

出　　处：《燃烧科学与技术》2022年第5期573-582,共10页Journal of Combustion Science and Technology

基　　金：国家自然科学基金资助项目(51876139;51606217);湖南创新型省份建设专项经费资助项目(2019RS2028).

摘　　要：纳秒脉冲放电可产生非平衡等离子体实现辅助燃烧.通过耦合零维等离子体动力学和燃烧反应动力学,建立了发动机纳秒脉冲放电等离子体助燃甲烷/空气的模型.研究表明:相同放电能量条件下纳秒脉冲放电可在上止点附近成功点燃当量比为0.5的稀混合气,而火花放电只能导致最高温度升高124 K,无法点燃缸内混合气.在纳秒脉冲放电条件下,低温时放电产生的激发态N_(2)(A^(3)Σ_(u)^(+))和O(1D)促进了O原子的生成.放电后期,累积的N2振动激发态在驰豫过程释放出了较多的热量,有利于稀燃条件下的点火.电流密度的增大提高了放电过程中激发态、自由基的浓度,发动机最高燃烧温度升高,点火延迟时间缩短,燃烧相位提前.Nanosecond pulsed discharge can produce nonequilibrium plasma to assist combustion.In this paper,a zero-dimensional model of methane/air combustion assisted by nanosecond pulse discharge plasma in internal com-bustion engines is established by coupling plasma dynamics and combustion reaction dynamics.The results show that with the same input energy,the nanosecond pulsed discharge can achieve successful ignition in lean-burn(φ=0.5)CH_(4)/air mixture near TDC,while spark discharge can only increase the maximum temperature about 124 K without successful ignition.The excited states N_(2)(A^(3)Σ_(u)^(+))and O(1D)produced during nanosecond pulsed discharging promote the production of O atoms at low temperature.In the late stage of discharge,the accumulated N_(2) vibrational excited states release more heat in the relaxation process,which is conducive to ignition.The higher current density causes the higher concentration of excited states and radicals leading to higher maximum temperature,shorter ignition delay time and advanced combustion phase.

关 键 词：等离子体助燃 纳秒脉冲放电 稀燃发动机 甲烷 等离子体动力学 

分 类 号：TK39[动力工程及工程热物理—热能工程]