摘要
在一台安装有进气道喷射甲烷和缸内直喷二甲醚(DME)的单缸光学发动机上,研究了DME喷射时刻对甲烷空气稀混合气压缩着火燃烧过程和火焰发展过程的影响。结果表明:在直喷DME下,气缸内的燃烧放热过程主要受到DME直喷时刻的控制。在-60°～-40°喷射DME时,放热率曲线呈单峰,在-30°～-15°喷射DME时,放热率曲线呈两阶段放热特征。气缸内的燃烧呈现自燃+火焰传播的特征。此外,DME喷射时刻还影响着火点的位置。随着DME喷射时刻的推迟,着火区域分布更加集中。与火花点燃甲烷燃烧相比,在压缩着火方式下,直喷DME能大幅提高甲烷/空气混合气燃烧初期的火焰传播速度,使燃烧放热过程加快。
The effect of DME injection timing on the compression ignition and flame development of lean methane-air mixture was studied on a single cylinder optical engine equipped with port methane injection and in-cylinder DME direct injection.Results show that in the case of DME direct injection,the combustion process in the cylinder is mainly controlled by DME injection timing.When the DME injection timing is in the range of 40°to 60°BTDC,the heat release rate curve shows a unimodal distribution and a bimodal distribution in the range of 15°to 30°BTDC.At this time,the in-cylinder combustion of DME/methane/air mixture shows the characteristics of self-ignition and flame propagation.Moreover,the DME injection timing also influences the location of ignition point.With the delay of DME injection timing,the distribution of ignition zone is more concentrated.Compared with port methane injection with spark ignition,under compression ignition conditions,the DME direct injection can significantly increase the flame propagation speed of methane-air mixture in the early stage of combustion,thus accelerating the combustion process.
作者
金超
何邦全
赵国兴
JIN Chao;HE Bangquan;ZHAO Guoxing(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China)
出处
《内燃机工程》
EI
CAS
CSCD
北大核心
2019年第1期21-27,共7页
Chinese Internal Combustion Engine Engineering
基金
国家重点基础研究发展计划项目(2013CB228403)
天津科委项目(15JCYBJC21300)~~
关键词
光学发动机
二甲醚
甲烷
燃烧
火焰
optical engine
dimethyl ether
methane
combustion
flame
