高圧噴射ディーゼル機関の燃焼解析 : 小噴孔径ノズルによる燃焼・排気改善効果

概要

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The effects of nozzle hole diameter on combustion and exhaust emissions were investigated using a single-cylinder DI diesel engine. (1) Exhaust NO_x and combustion period depend only on injection pressure and not on nozzle hole diameter, because with a small-hole-dia. nozzle the effect of reduced mean injection rate is canceled out by the effect of promoted mixture formation and combustion. (2) With decreasing injection pressure, smoke sharply increases with a large hole-dia. nozzle but does not increase with small hole diameter of less than 0.20 mm. The decrease of injection pressure reduces NO_x emission. (3) The effect of suppressing the increase of smoke with a small-hole-dia. nozzle is considered to be caused mainly by the rapid temperature rise over about 1800℃ in the fuel-rich region near the spray in flame. (4) With the conversion of a deep bowl combustion chamber to a shallow-dish one, smoke increases as injection pressure decreases, in spite of the use of a small-hole-dia. nozzle, due to the reduction of mixing effect.
社団法人日本機械学会の論文
1994-09-25