Impact of flash boiling multiple injections timing on the combustion and thermal efficiency of a gasoline direct injection engine under lean-burn
Impact of flash boiling multiple injections timing on the combustion and thermal efficiency of a gasoline direct injection engine under lean-burn
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稀薄燃烧下闪沸腾多次喷射正时对汽油直喷发动机燃烧及热效率的影响
DOI：
10.1016/j.fuel.2021.121450
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发表时间：
2021-11
期刊：
影响因子：
7.4
通讯作者：
Min Xu
中科院分区：
文献类型：
--
作者：
Zhe Sun;Qinglin Xu;Mingli Cui;Mohamed Nour;Xuesong Li;David L.S. Hung;Min Xu
直喷式火花点火发动机（DISI）的精益燃烧方式可以提高发动机的热效率。然而，它表现出火焰传播缓慢和燃烧不稳定，这与混合物的分布密切相关。多次注入可以改善对缸内电荷分布的控制，从而改善燃烧模式。此外，多次喷射可以减少喷雾冲击并增强压缩行程中的湍流，特别是在喷射后期，但时间不足以使喷雾蒸发。闪沸条件下的喷油促进了后期喷油的汽化和喷流相互作用。在光学DISI发动机上研究了闪沸多次喷射对稀薄汽油/空气混合气燃烧的影响。本文采用Mie散射、CFD、高速成像和火焰图像后处理模型对喷雾特性、喷雾-气流相互作用、火焰传播和CH*数字强度进行了研究。结果表明，与过冷单次喷射相比，闪沸多次喷射显著减轻了液体喷射强度，汽化速率提高，喷雾撞击减少，与翻滚流的相互作用更好。当第二次喷射和最高转鼓比点及时同步时，如800转/分时260°bTDC和1500转/分时280°bTDC，发动机性能和燃烧达到最佳。因此，闪沸多次注入可有效提高热效率，分别提高54.65%和11%。CH*数字强度和放热结果表明，闪沸多次注入能有效改善DISI发动机的稀燃运行。
Lean burn mode of direct injection spark ignition engines (DISI) can improve the engine's thermal efficiency. However, it showed slow flame propagation and combustion instabilities which are strongly related to mixture distribution. Multiple injections can improve control over in-cylinder charge distribution and consequently on burn mode. Additionally, multiple injections can reduce spray impingement and enhance the turbulence in the compression stroke, particularly with late injection, but the time is not enough for spray evaporation. Fuel injection under flash boiling conditions boosts fuel vaporization and spray-airflow interaction of the late injections. This study investigates the effect of flash boiling multiple injections on the combustion of lean gasoline/air mixture in an optical DISI engine. This work uses Mie scattering, CFD, high-speed imaging, and flame images postprocessing model to investigate spray characteristics, spray-airflow interaction, flame propagation, and CH* digital intensity. The results reveal that flash boiling multiple injections has significantly mitigated the liquid spray intensity indicates the elevated rate of vaporization with reduced spray impingement and better interaction with the tumble flow compared to the subcooled single injection. The optimal engine performance and combustion were achieved when the second injection and highest tumble ratio point were timely synchronized, for example, 260°bTDC at 800 rpm and 280°bTDC at 1500 rpm. Thus, flash boiling multiple injections can effectively enhance the thermal efficiency by 54.65% and 11%, respectivly. The CH* digital intensity and heat release showed that flash boiling multiple injections could effectively improve the lean-burn operation of the DISI engine.
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过冷和过热工况下火花点火直喷喷油器近喷嘴喷雾和喷雾塌陷特性
影响因子：
7.4
作者：
Wu Shengqi;Xu Min;Hung David L. S.;Li Tianyun;Pan Hujie
通讯作者：
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影响因子：
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Shangze Yang;Xuesong Li;D. Hung;M. Arai;Min Xu
DOI：
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发表时间：
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期刊：
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影响因子：
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作者：
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通讯作者：
G. Zizak
影响因子：
7.4
作者：
Di Xiao;Shuyi Qiu;David Hung;Xuesong Li;Keiya Nishida;Min Xu
通讯作者：
Min Xu
影响因子：
7.4
作者：
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通讯作者：
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