Abstract
DI (direct injection) systems have been studied to improve thermal efficiency of gasoline engines. The analysis of spray behavior is important to examine the combustion characteristics of DI gasoline engines because fuel-air mixture formation is controlled by spray characteristics and gas motion. In this study, the characteristics of a fan-shaped spray, such as the droplet size, its velocity and the droplet-size distribution were simultaneously measured on a 2D plane by using an improved ILIDS (Interferometric Laser Imaging for Droplet Sizing) method. As a result, interesting relationships between the droplets diameter and the velocity were found. In addition, numerical analysis of a fan-shaped spray was conducted and the results were compared to the measured results. In numerical analysis, the nozzle internal flow was predicted by using VOF (Volume of Fluid) model that can simulate the two-phase flow inside the nozzle to give the liquid film formation process outside the nozzle. Using the results of VOF model for the initial conditions, numerical analysis of the spray by DDM (Discrete Droplet Model) was carried out to examine the droplets breakup process.
Keywords:Fan-shaped spray, ILIDS, Droplet size, Droplet velocity, Droplet distribution