Study on individual spray plume characteristics of multi-hole direct injection spark ignition (DISI) injector using cross-sectional area

Abstract

In a direct injection engine system, the fuel spray characteristics including the uniformity of air-fuel mixture significantly affects the combustion characteristics and the generation of harmful emissions. To optimize engine performance, a variety of studies on spray characteristics have been conducted in for years. However, it is difficult to identify the individual spray plumes characteristics of multi-hole GDI injectors due to interference from spray. In this study, the spray pattern was used to measure the uniformity and the accurate spray targeting of the individual spray. As the distance from the nozzle tip to the measurement section increases, the spray area increases due to fuel atomization and scattering. As a result, as the distance from the nozzle tip to the measurement section increases, the uniformity of the spray decreases while the deviation of the spray center increases. When the injection pressure is increased, the momentum of the spray droplet is increased, and the influence of the ambient air resistance is reduced, leading to improved spray uniformity. In addition, the method of measuring the spray angle of each individual spray plume was presented through the spray pattern image in the GDI injector with high interference between the spray plumes. High injection pressure can reduce the spray angle deviation of the individual spray plume, increasing spray uniformity between injector holes. These results can be used to establish a spray strategy with which to increase the accuracy of spray targeting in the combustion chamber and minimize collision with the combustion chamber and piston wall.