\r王利民^{1, 2}，韩义勇^{1, 2}，刘宗宽¹，赵万辉¹，周 磊¹，卫海桥\r¹\r
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AuthorsHTML:\r王利民^{1, 2}，韩义勇^{1, 2}，刘宗宽¹，赵万辉¹，周 磊¹，卫海桥\r¹\r
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AuthorsListE:\rWang Limin^{1, 2}，Han Yiyong^{1, 2}，Liu Zongkuan¹，Zhao Wanhui ¹，Zhou Lei¹，Wei Haiqiao \r¹\r
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AuthorsHTMLE:\rWang Limin^{1, 2}，Han Yiyong^{1, 2}，Liu Zongkuan¹，Zhao Wanhui ¹，Zhou Lei¹，Wei Haiqiao \r¹\r
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Unit:\r\r1. 天津大学内燃机燃烧学国家重点实验室，天津 300072；\r
\r\r2. 玉柴股份有限公司，玉林 537005\r
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Unit_EngLish:\r1. State Key Laboratory of Engines，Tianjin University，Tianjin 300072，China；
2. Yuchai Machinery Co.，Ltd.，Yulin 537005，China\r
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Abstract_Chinese:\r\r柴油喷雾燃烧是个复杂的物理化学过程，尤其是低温条件下湍流燃烧仍有许多未知的现象．本文基于大涡模拟方法开展了不同环境温度下正十二烷喷雾火焰燃烧过程的模拟研究．首先，通过与喷雾燃烧基础数据库\rEngine Combustion Network\r(\rECN\r)\r网站上试验数据对比，包括喷雾发展过程、着火延迟期和火焰浮升长度试验值，发现\rLES\r-\rLEM\r模型能够捕捉喷雾发展过程和燃烧过程，并且与试验数据非常接近．其次，本文深入分析了喷雾火焰中的低温燃烧过程，研究发现，提高初始温度，第\r1\r阶段着火延迟期和总的着火延迟期均缩短，而第\r2\r阶段着火延迟期变长，同时提高初始环境温度，出现放热率峰值的混合气浓度增加．酮类过氧化物和甲醛可以表征喷雾火焰中的多阶段着火过程，在着火延迟期附近，随着初始温度升高，酮类过氧化物\r(\rOC₁₂H₂₃OOH\r)\r质量分数峰值逐渐远离当量比混合物分数\r(\r\rZ\r\r_\rst\r\r)\r向浓混合气方向发展．最后，本文探究了初始温度对整体燃烧放热过程和主要组分，包括碳烟标识物\rC₂H₂\r生成的影响．研究发现\r900K\r条件下\rC₂H₂\r累积质量高于低温条件下的累积质量，这主要是由于\r900K\r条件下着火延迟期和火焰浮升长度缩短，卷吸进来的空气质量减少，燃油与空气混合变差，产生了有利于\rC₂H₂\r形成更广泛的浓混合气区域．\r\r
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Abstract_English:\r\rDiesel spray flame is a complicated physics and chemistry process\r．\rParticularly at low-temperature combustion conditions\r，\rthere are many unknown combustion phenomena\r．\rTherefore\r，\rin the present work\r，\ra numerical study was performed to investigate the combustion process of n-dodecane spray flame at different ambient temperatures by large eddy simulation\r(\rLES\r)\r．\rFirst\r，\rfor validation of the accuracy of the model\r，\rthe simulated values were compared with the experimental data from the Engine Combustion Network\r，\rincluding the spray development process\r，\rignition delay time\r，\rand flame lift-off length\r．\rResults showed that the LES-LEM can accurately capture diesel spray and combustion characteristics\r，\rwhich were close to the experimental data\r．\rThe low-temperature combustion process of spray flame was then deeply analyzed\r．\rResults showed that increasing the initial temperature reduced the ignition delay time at first stage and overall ignition delay time\r，\rand the ignition delay time was prolonged at the second stage\r．\rMeanwhile\r，\rthe peak of heat release rate will occur in the rich-mixture region with increasing initial temperature\r．\rKetone peroxides and CH₂O represented the multi-stage ignition process of the spray flame\r．\rNear the ignition delay time\r，\rthe peak of mass fraction of OC₁₂H₂₃OOH gradually moved toward a rich-mixture position far from the stoichiometric mixture\r．\rIn addition\r，\rwe also studied the effects of initial temperature on the total heat release and the production of key intermediates\r，\rsuch as C₂H₂\r．\rThe accumulated mass of the C₂H₂ in the soot precursors at 900K was larger than that under low-temperature conditions\r．\rThis was because the ignition delay time and flame lift-off length were reduced at higher initial temperature\r，\rresulting in a relatively worse mixing of fuel and air and the formation of a more rich mixture\r．\rAs a consequence\r，\rthe soot formation became beneficial\r．\r\r
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Keyword_Chinese:喷雾燃烧；大涡模拟；低温燃烧；碳烟\r

Keywords_English:spray combustion；large eddy simulation(LES)；low-temperature combustion；soot\r


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