Comprehensive Spray Characteristics of Water in Port Fuel Injection Injector

The objective of this study was to compare the injection and spray characteristics of water with n-heptane using a port fuel injection (PFI) system. In this study, the injection pressure was changed to 0.3–0.9 Mpa and the energizing duration was changed to 0.5–4 ms. To investigate spray characteristics, the injection quantities of n-heptane and water were measured. Macroscopic spray characteristics were determined through spray visualization. The Sauter mean diameter (SMD) and velocity of spray droplets were measured with a phase Doppler anemometry (PDA) experiment. Spray tip penetration, spray angle, SMD of droplets, and spray droplet velocity were compared. As the injection pressure increased, the injection quantity and the droplets velocity increased. However, the spray tip penetration, SMD of the droplet, and the spray angle decreased. The increase in energizing duration led to an increase in the injection quantity without affecting other spray characteristics. The higher density of water also increased injection quantity, resulting in a decrease in spray tip penetration and increases of SMD and velocity of spray droplets due to high viscosity and surface tension of water.