缸内直喷CNG发动机喷射方式对火焰传播特性及性能的影响  

Effect of Injection Mode on Flame Propagation Process and Performance in GDI CNG Engine

作　　者：林学东[1] 黄丫[1] 袁方恩[1] 

机构地区：[1]吉林大学汽车仿真与控制国家重点实验室,吉林长春130022

出　　处：《内燃机学报》2012年第5期440-445,共6页Transactions of Csice

摘　　要：火焰传播是点燃式发动机的主要燃烧方式,为了有效控制缸内直喷CNG发动机更稳定的稀薄燃烧过程,以实现高效率低排放,利用试验用单缸光学发动机,采用双喷射器缸内直喷CNG方式,在双火花塞点火的条件下,分析研究了不同喷射方式对火焰形成及传播特性以及发动机性能的影响.结果表明,双点点火时,缸内气流对首先形成的火焰具有"牵引"作用,而两个火焰由于形成时刻不同传播方式就有区别,且两个火焰之间具有"挤压或推动"作用,由此影响整体火焰传播速度;缸内火花塞附近混合气浓度越浓或不均匀性越大,循环波动越小,燃烧更稳定,但随混合气浓度分布不均匀性的增加,NOx排放也增加,表明基于混合气浓度不均匀性分布特性的燃烧过程中,NOx的生成机理不仅与高温富氧条件有关,而且还与浓度场分布特性有直接的关系.Flame propagation is the main combustion mode in spark-ignition engine. To effectively control the stable lean combustion in a direct-injection CNG engine and achieve high-efficient low-emission com- bustion, a lean burn CNG direct-injection optical engine coupling with double injectors and double spark plugs was used to study the effect of injection mode on flame propagation process and engine performance. Results show that, with ignition at two positions, the air-flow in cylinder promotes early formed flame, and leads to different propagation patterns between the two flames. Extrusion and pushing effect between two flames are existed, and these affect the overall flame propagation speed, particularly near the spark plug. High mixture concentration leads to small cyclic variations. However, the increase in mixture con- centration non-uniform will increase NOx emission. Therefore, controlling the distribution of mixture concentration is the key to control the lean burn, and the non-uniform of mixture concentration directly affect NOr formation.

关 键 词：CNG发动机 缸内直喷 稀薄燃烧 火焰传播特性 NOX排放 

分 类 号：TK411.2[动力工程及工程热物理—动力机械及工程]