Fluorescent-PIV Spray/Air interaction analysis of high-pressure gasoline injector 2007-01-1825

Mixture formation in modern SI engines is still lacking effective means of control. Widely known air, wall and spray-guided mixture formation solutions have been applied more or less successfully by different manufacturers. Spray-guided systems have the advantage of requiring only a precise control of the spray features, allowing for simpler air intake devices. But air entrainment by spray is not always sufficiently effective to create the mixing conditions of a good combustion. This paper aims at further understanding the processes of air entrainment by sprays. A pressure vessel with optical access is equipped with a gasoline injector tested for different injection and ambient pressures, injection times and other parameters. A fluorescent/MIE dual PIV technique is used to obtain simultaneous 2D velocity fields of spray droplets and seeding particles of surrounding gas. Fuel used is iso-octane, doped with fluoranthene as fluorescent tracer. Simultaneous velocity fields of spray and air are presented in a parametric study. MIE scattering images of spray, simultaneously obtained with fluorescent images, are presented allowing estimating relative 2D Sauter Mean Diameter values in different zones of spray. Relative size and absolute velocity measurements of droplets are analyzed to discuss on spray-guided systems features that achieve effective control of mixture formation.