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| Mixture Formation with Split Injection and Its Effect on Combustion and Emissions of Diesel Engines |
| DOI：10.13949/j.cnki.nrjgc.2019.04.007 |
| Key Words:diesel engine pilot injection swirl flow squish flow fuel/air mixing |
| Author Name | Affiliation | | LI Fengchao, WANG Tianyou, LI Lei, SHANG Tansu, LIU Guoqiang, SUN Kai | 1.State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
2.Luoyang Tractor Research Institute Co., Ltd., Luoyang 471039, China
3.State Key Laboratory of Power System of Tractor, Luoyang 471039, China) |
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| Abstract:The fuel-air mixture formation and combustion of an off-road direct-injection diesel engine with split injection were computationally investigated, and the effects of squish and swirl flows on the equivalence ratio distribution and combustion of the fuels from both pilot and main injections were analyzed. The results show that the squish flow tend to transport the pilot-injected fuel vapor into the piston bowl when properly increasing the interval between pilot and main injections(20° in crank angle) and a moderate swirl flow(from 1.5 to 2.0) can shift the pilot injection sprays towards the regions between two adjacent main-injection sprays. Remarkably, both of the two effects can reduce the overlap of the pilot and main injections, and the heat released from the pilot injection combustion can further accelerate the mixing and combustion processes of the main injection. An optimal pilot injection strategy together with a proper swirl ratio can increase engine power with reduced soot emissions, although the NOx emissions will be unfavorably increased. |
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