直接噴射式ディーゼル機関における排気特性と火炎挙動に及ぼす過濃高乱流燃焼の影響

概要

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This study tried to reduce NO_x and particulate emissions simutaneously in a high speed direct-injection diesel engine. Fuel-rich combustion was used to reduce NO_x emission at initial combustion stage and high turbulence combustion was used to reduce particulate emission at diffusion combustion stage. Experiments were carried out to investigate the effects of high squish combustion chambers with small throat on combustion process and exhaust emissions. Results showed that in the high squish combustion chamber, both NO_x and particulate emissions reduced with retarded injection timing. Endoscopic high speed photography was employed to analyze experimental results. In the original combustion chamber at the early combustion stage, the high luminosity flame tended to spread out of the cavity. Fuel-rich mixture burned slowly over the piston crown. In the high squish combustion chamber, flame rotated violently around the bowl. Fuel-rich mixture was kept beneath the squish lip, and was mainly oxidized inside the bowl. This combustion phenomenon was considered to be one of the reasons for low particulate emission in high squish combustion chambers.
一般社団法人日本機械学会の論文
1999-09-25