Clarification and Control of Ignition Mode Transition by Addition of Turbulence

通过添加湍流来澄清和控制点火模式转变

基本信息

批准号：
15560181
负责人：
ISHIYAMA Takuji
金额：
$ 2.37万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560181/
关键词：
Internal Combustion Engines Fuel Spray Compression Ignition Mixing Process Modelling

项目摘要

This study aims at clarification of combustion phenomena and obtaining control strategies for direct-injection Premixed Charge Compression Ignition(DI-PCCI) combustion to realize low NOx(nitrogen oxides) and PM(particulate matters) emissions with controllable ignition and heat release process. To this end, we attempted to utilize intense turbulence, which would force spray ignition into two-stage ignition mode found in ignition of homogeneous fuel-air mixture.To obtain fundamental understanding of ignition process in DI-PCCI, effects of ambient and injection conditions were investigated for n-heptane spray combustion in a constant volume vessel. Ambient pressure and temperature were selected so as to simulate PCCI-like ignition and heat release process. Changing oxygen concentration and injection conditions, homogeneity in mixture concentration was varied at the hot flame initiation. A total gas sampling system was constructed to measure NOx concentration during heat release. A spray ignition and combustion model was developed based on stochastic turbulent mixing model with a simplified n-heptane oxidation scheme to understand the relation between mixture formation and chemical reaction progress.Weak mixing with larger nozzle orifices and lower injection pressure provides earlier onset of hot flame, while intense mixing with smaller orifices and higher injection pressure gives delayed hot flame and reduced heat release rate. Experiments with total gas sampling technique reveals that quite low NOx production connects to the intense mixing case with delayed hot flame. Analysis of histories of equivalence ratio and temperature in fuel-air mixture with the aid of a ignition and combustion model suggests that delayed ignition and reduced heat release rate are given in the case that entire mixture falls into lean region where the reaction speed decreases with decreasing equivalence ratio.

这项研究旨在阐明燃烧现象并获得直接注射预混合电荷压缩点火（DI-PCCI）燃烧的控制策略，以实现具有可控点火和热量释放过程的低NOx（氮氧化物）和PM（颗粒物）排放。为此，我们试图利用强烈的湍流，这将迫使喷火点火进入均匀的燃料空气混合物点火时发现的两阶段点火模式。要获得对DI-PCCI的点火过程的基本了解，研究了环境和注射条件的影响，以实现恒定体积容器中的N-甲烷喷雾燃烧的影响。选择环境压力和温度以模拟PCCI样点火和热量释放过程。氧气浓度和注射条件的变化，混合浓度的均匀性在热火焰开始时变化。构建了一个总的气体采样系统，以测量热量释放期间的NOx浓度。基于随机的湍流混合模型，开发了喷雾点火和燃烧模型，具有简化的N甲烷氧化方案，以了解混合物形成与化学反应进度之间的关系。与较大的喷嘴孔口和较低的喷射压力的汗水混合可提供较早的热火焰发作，而强烈的孔口和较小的注射压力和较高的热压力降低热释放率和延迟的热释放速度。总体气体采样技术的实验表明，NOX的生产相当低，与延迟的热火焰相连。借助点火和燃烧模型对燃料空气混合物中的等效比和温度的历史分析表明，在整个混合物落入瘦肉区域中，给出了延迟的点火和降低热速率，而反应速度随着等效比的降低而降低。