MODELING OF n-HEPTANE SPRAYS INJECTED THROUGH MULTI-HOLE TYPE GDI INJECTOR

Abstract

The purpose of this study is to investigate the spray plume shape and fuel atomization characteristics of a gasoline direct injection (GDI) system. The spray characteristics were analyzed according to ambient gas pressure, temperature and injection pressure. The multi-hole type GDI system was simulated to enhance the fuel atomization performance. A multi-dimensional computational fluid dynamics code (KIVA-3V) was implemented to predict the two-dimensional spray behavior. The predicted spray penetration, velocity distribution of ambient gas, droplet size and spray plume shape results were compared with the experimental results to verify the accuracy of numerical models. The Kelvin-Helmholtz, Rayleigh-Taylor breakup model and radius-of-influence collision model were applied for the prediction of spray behavior and characteristics. It was found that the ambient gas pressure had a significant influence on spray tip penetration length and spray plume shape. In addition, the Sauter mean diameter was decreased and vortex became stronger with higher injection pressure. On the whole, the present calculation models showed good agreement with experiments in terms of spray shape and size distributions.