Vol.36 No.4(2001.12)
Special Issue / Research Report
Improvement of Emission and Fuel Consumption for Direct Injection Gasoline Engine

Spray Characteristics of Slit Nozzle for DI Gasoline Engines
Kiyomi Kawamura, Norikazu Katsumi,
Reiko Ueda

Direct injection gasoline engines have been developed by several manufacturers for improvement of the fuel economy and exhaust emissions. These direct injection gasoline engines utilize air motion such as swirl or tumble to lead the mixture to the spark plug. However, the suction port generating the swirl or tumble sometimes produces a lower volumetric efficiency compared to the straight port. Therefore, a new combustion concept, which does not depend on air charge motion, was proposed. A slit nozzle was developed to realize this new concept. The nozzle has a rectangular orifice and forms a thin fan-shaped spray. The spray characteristics of the slit nozzle were evaluated and compared to that of the swirl nozzle. The following results were obtained from the experimental analysis. (1) The spray penetration increases with increasing slit thickness. (2) The effect of the slit thickness on the spray drop size is small at the higher injection pressures. (3) The features of the slit nozzle include a high spray penetration, wide diffusion spray and fine atomization compared to the swirl nozzle.