Influence of nozzle geometry on ignition and combustion for high-speed direct injection diesel engines under cold start conditions
Influence of nozzle geometry on ignition and combustion for high-speed direct injection diesel engines under cold start conditions
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DOI：
10.1016/j.fuel.2011.06.006
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发表时间：
2011-11
期刊：
影响因子：
7.4
通讯作者：
J. Desantes;J. M. García-Oliver;J. M. Pastor;J. G. Ramírez-Hernández
中科院分区：
文献类型：
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作者：
J. Desantes;J. M. García-Oliver;J. M. Pastor;J. G. Ramírez-Hernández
低温启动（低于0°C）是当前和不久的将来柴油发动机技术的重要问题。环境温度过低会导致小型柴油发动机启动时间过长或完全失火，从而导致污染物排放量增加。本文研究了在辉光塞辅助冷启动条件下，喷嘴几何形状对点火和燃烧过程的影响。这项研究是在一个光学可接近的发动机中进行的，该发动机适应于在低环境温度下启动时再现与真实发动机相对应的缸内条件。冷启动问题可分为喷嘴几何形状影响的点火和主燃烧过程两部分。增大喷油速度和减小喷油质量会降低点火概率，这是由孔径较小和孔口数较大引起的。当使用喷嘴时，燃烧速度增加，产生更高的动量，改善混合条件。由于这些原因，在这些条件下的解决方案必然涉及点火和燃烧过程之间的权衡。
Starting at low temperatures (below 0°C) is an important issue for current and near future diesel engine technology. Low ambient temperature causes long cranking periods or complete misfiring in small diesel engines and, as a consequence, an increased amount of pollutant emissions. This paper is devoted to study the influence of nozzle geometry on ignition and combustion progression under glow-plug aided cold start conditions. This study has been carried out in an optically accessible engine adapted to reproduce in-cylinder conditions corresponding to those of a real engine during start at low ambient temperature. The cold start problem can be divided in two parts in which nozzle geometry has influence: ignition and main combustion progress. Ignition probability decreases if fuel injection velocity is increased or if the amount of injected mass per orifice is reduced, which is induced by nozzles with smaller hole diameter or higher orifice number, respectively. Combustion rates increase when using nozzles which induce a higher momentum, improving mixture conditions. For these reasons, the solution under these conditions necessarily involves a trade-off between ignition and combustion progress.