利用火花点火式快速压缩装置进行天然气直喷分层燃烧可行性的研究

摘要

Feasibility of compression natural gas direct-injection (CNG DI) stratified combustion is investigated by using a rapid compression machine.Results show that CNG DI stratified combustion has the short initial flame development duration and main burning duration and high pressure rise due to combustion caused by the charge stratification.Stratified combustion can extend the lean combustion limit to very lean region.CO increases steeply with the increase in equivalence ratio φ when φ is larger than 0.8 due to the excessive stratification and NOx peak value shifts to the region of low φ due to charge stratification.Combustion efficiency maintains more than 0.92 in the range of φ from 0.1 to 0.9 and it deteriorates at very low φ due to bulk quenching and at large φ due to excessive stratification.The combustion efficiency calculated from combustion products shows good agreement with that obtained from the heat release analysis.Thus CNG DI is considered to have much potential in a spark-ignition engine on the basis of wide operation range of φ and high energy conversion efficiency.%利用快速压缩装置进行了天然气直喷分层燃烧可行性的研究.结果表明:天然气分层燃烧具有短的初期火焰发展期和主燃期以及高的燃烧压力.分层燃烧可使稀燃极限延伸到很小的当量比.由于过度分层,CO在当量比大于0.8时急剧增加,而NOx的峰值也因充量分层而出现在小当量比处.燃烧效率在当量比处于0.1～0.9范围时高于0.92,在极小当量比时由于未燃混合气淬熄,在当量比时由于过度分层而使燃烧效率降低.根据燃烧产物计算的燃烧效率与根据放热分析获得的燃烧效率一致.因此,天然气直喷分层燃烧在宽广的当量比范围内可望实现高效燃烧火花助燃发动机的宽广的高效燃烧.