320 小型直噴ディーゼル機関におけるアフター噴射燃焼によるスモーク低減メカニズム(OS-1 直噴ディーゼル機関,研究発表講演)

概要

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Multiple-injection is a remarkable technology towards further reduction in toxic exhaust emissions from DI diesel engines. After-injection, which injects a small amount of fuel immediately after the end of main injection, reduces smoke effectively. In this study, the smoke reduction mechanism caused by the after-injection was examined, using in-cylinder shadow-graph observation. Flame temperature and velocity were also calculated by picture processing analysis, such as two-color method and cross correlation method, respectively. Without after-injection, the flames in the squish area simply extinguish in the later part of combustion period, with little movement and deformation due to the attenuated swirl. For the case with after-injection, the flame jets of the after-injection develop behind the previously exited flames in the squish area, then catch up to them and keep the region reactive. Picture processing analysis revealed that this promotion in oxidization process was mainly caused by the increase in temperature due to the flame jets of after-injection.
2005-03-18