Effect of injection timing on the ignition process of n-heptane spray flame in a methane/air environment
Effect of injection timing on the ignition process of n-heptane spray flame in a methane/air environment
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甲烷/空气环境下喷射正时对正庚烷喷雾火焰点火过程的影响
DOI：
10.1016/j.fuel.2019.02.086
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发表时间：
2019-06
期刊：
影响因子：
7.4
通讯作者：
Zhou Lei
中科院分区：
文献类型：
--
作者：
Wei Haiqiao;Zhao Wanhui;Qi Jiayue;Liu Zongkuan;Zhou Lei
人们对使用先导燃料作为点火源来提高天然气发动机的性能非常感兴趣。燃油喷射正时是影响发动机燃烧相位和排放特性的关键因素。在本研究中，采用大涡模拟（LES）方法，在类似发动机的条件下，在定容燃烧容器中进行了喷射时间对甲烷/空气环境中正庚烷喷射火焰发展的影响。结果表明，喷射缓速剂加速了正庚烷喷雾的点火，缩短了正庚烷与甲烷/空气混合物的点火间隔。通过引入火焰指数（FI）来区分预混燃烧和非预混燃烧对热量释放的贡献。此外，通过零维仿真的灵敏度分析，探讨了缓速喷射导致提前点火的原因。结果表明，虽然甲烷的加入延缓了正庚烷的点火，但甲烷/空气混合物的预点火氧化反应在正庚烷注入之前就已经发生，从而使温度和压力升高，产生大量的中间自由基，从而促进了正庚烷的点火。此外，正庚烷喷射火焰反过来进一步点燃甲烷/空气混合物并诱导高温燃烧。结果还表明，温度对着火的影响最大，其次是重要中间物质甲醛（CH2O）的影响，而压力的影响较小。本研究为深入了解喷射正时对双燃料发动机燃烧的影响提供了理论基础。
There is significant interest in using pilot fuel as a source of ignition to enhance the performance of a natural gas engine. The pilot fuel injection timing is a critical factor that influences the combustion phasing and emissions characteristics. In this study, the effect of injection timing on the development of n-heptane spray flame in a methane/air environment is performed by using large eddy simulation (LES) in a constant-volume combustion vessel under engine-like conditions. The results indicate that injection retarding accelerates the ignition of n-heptane spray and reduces the interval between the ignition of n-heptane and methane/air mixture. The contributions of premixed and non-premixed combustion on heat release are distinguished by introducing the flame index (FI). Furthermore, the reason why retarding injection leads to earlier ignition is investigated by sensitivity analysis in a zero-dimension simulation. It is concluded that although methane addition delays the ignition of n-heptane, the pre-ignition oxidative reactions of methane/air mixture occurs prior to the n-heptane injection, thereby increasing the temperature and pressure and producing significantly intermediate radicals and consequently promoting the n-heptane ignition. Additionally, the n-heptane spray flame, in turn, further ignites the methane/air mixture and induces the high-temperature combustion. The results also indicate that the influence of temperature on the ignition is maximum, which is followed by the influence of important intermediate species, formaldehyde (CH2O), while the influence of pressure is minor. The present study provides a theoretical basis for an in-depth understanding of the effect of injection timing on the combustion of dual-fuel engines.
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影响因子：
4.4
作者：
Zhaoyu Luo;C. Yoo;E. Richardson;Jacqueline H. Chen;C. Law;T. Lu
通讯作者：
Zhaoyu Luo;C. Yoo;E. Richardson;Jacqueline H. Chen;C. Law;T. Lu
DOI：
10.4271/2013-24-0112
发表时间：
2013-09
期刊：
--
影响因子：
--
作者：
S. Schlatter;B. Schneider;Y. Wright;K. Boulouchos
通讯作者：
S. Schlatter;B. Schneider;Y. Wright;K. Boulouchos
不同温度和密度正十二烷分流喷射火焰结构的大涡模拟
影响因子：
1.9
作者：
Zhou Lei;Zhao Wanhui;Wei Haiqiao
通讯作者：
Wei Haiqiao
DOI：
10.2514/6.2014-1020
发表时间：
2014
期刊：
--
影响因子：
--
作者：
E. Demosthenous;G. Borghesi;E. Mastorakos;R. Cant
通讯作者：
E. Demosthenous;G. Borghesi;E. Mastorakos;R. Cant
影响因子：
10.4
作者：
M. Selim
通讯作者：
M. Selim