Comparison of spray characteristics of gasoline and water-in-gasoline mixture at elevated fuel temperature conditions

Abstract

With the advent of the era of ultra-high thermal efficiency and ultra-low emission internal combustion engines, water injection technology is the key to solving the knocking problem and breaking the technical bottleneck. Water-in-oil mixture shows great potential as a special water injection technology for avoiding the huge cost of engine modification and the application of the flash-boiling spray, which brings more possibilities for the improvement of atomization quality, the formation of fuel–air mixture and the combustion. In this work, the spray development process of gasoline(G100) and water-in-gasoline(G70) was explored. Spray characteristics, including spray penetration, spray cone angle, spray area, minimum energy for atomization and spray particle size distribution, were investigated at elevated fuel temperature conditions (25 ~ 140 °C). The results show that as the temperature of the mixture rises, the spray pattern gradually assumes a collapsed shape, which will be prominent at the initial injection by the intervention of water after 100 °C. There are critical temperatures of 75 °C(G100) and 90 °C(G70), above which the spray penetration is remarkably reduced and the spray cone angle and spray area of G70 are enormously increased but that of G100 are diminished. The minimum energy for atomization and SMD (Sauter Mean Diameter) decrease as the temperature of the mixture rises. There exists a critical temperature of 90 °C, above which the particle size span decreases sharply and the small particle size droplets disappear quickly.