This study investigates a fuel spray development process of gasoline–biodiesel blended fuel (GB) in macroscopic and microscopic scales. Long-distance microscopy and shadowgraph were utilized as optical methods to capture the highly transient spray development. Different injection pressures were tested, which ranged from 40 to 120 MPa with a fuel temperature of 323K. Tested four fuels were neat gasoline and biodiesel addition (5%, 20%, 40% by volume) to gasoline in three different ratios. The results regarding the development process for the initial spray near the nozzle show that the spray penetration and the spray tip velocity both decreased with decreasing biodiesel blending ratio. This relationship appears to be due to the associated differences in the mass flow rate and the radial direction velocity vector of the spray. In addition, the different spray tip velocities at the start of spraying result in different atomization regimes between the fuels. The GB fuels with the low biodiesel blending ratio were disadvantaged in spray atomization due to their lower spray penetration and tip velocity. However, as the injection pressure increased, the differences in microscopic spray penetrations between the fuels became smaller, along and there were changes in the atomization characteristics.
Keywords gasoline, biodiesel, sprays, shadowgraph, long distance microscopy, atomization