Effect of nozzle hole design on injector wetting and particulate emissions in a GDI engine

Abstract

An experimental study was carried out to investigate the effect of nozzle hole design on injector nozzle tip wetting and particulate emissions in a turbo-charged direct injection gasoline engine. For this purpose, 3 nozzle hole design concepts were newly developed. Each concept can be explained as classical step-hole nozzles with various step-hole diameters, a tapped step hole design, and a nozzle without step-hole, respectively. Nozzle tip wetting of each concept was visualized using a laser induced fluorescence technique. A vehicle test was carried out on a vehicle dynamometer bench with in-cylinder visualization optics detecting luminous diffusion flames. Consequently, the behavior on nozzle wetting and its effect on particulate emissions for each nozzle design concept were analyzed. Results showed that injectors without step hole and with smaller step hole cavity have significant advantages on particulate emissions caused from injector tip wetting.