Spray pattern optimization for gasoline direct injection engine

Spray pattern is an important design parameter for GDI multi-hole injector. Spray pattern affects fuel-air mixing, intake air flow, turbulent intensity, fuel film development. Especially for side-mounted multi-hole GDI injector, fuel film can be formed on intake valves depending on spray targeting. Proper spray pattern design can not only reduce fuel film formation, exhaust emission, and fuel loss to intake port but also increase mixture homogeneity and flammability. In this study, spray pattern was optimized by modifying nozzle orientation. Mass flow from each nozzle and the amount of cavitation were assumed to be equal for each nozzle. Thus, effective nozzle area of each nozzle is equal. For analyzing three dimensional multi-physics, KIVA 3V release2 was utilized. Before three dimensional modeling, motoring pressure and intake charge cooling effect was validated with experimental data. Also, spray breakup model constants were calibrated using spray tip penetration from experiment. Mixture homogeneity and fuel loss to intake port was the main factor for spray pattern optimization. First, wide-open throttle (WOT) operating condition which utilizes homogeneous charge was investigated. Optimization for part load condition was also carried out. Open-type spray pattern which shows better dispersion characteristics was well-suited to increase mixture homogeneity.