EFFECTS OF AMBIENT CONDITIONS ON DUCTED SPRAYS WITH DIESEL AND GASOLINE

The method of installing a duct in the front of the injector nozzle has been proved to be effective. The effects of fuel properties on ducted fuel injection (DFI) were investigated. The gas–liquid two phases of spray under different working conditions were captured using an optical testing system in a constant volume combustion chamber. Increasing the back pressure had a promotional effect on the DFI spray, enhancing the spray penetration and spray area relative to the free spray for diesel and gasoline. Also, increasing ambient temperature promoted the effect of DFI spray for gasoline by increasing the spray penetration and spray area. However, the boosting effect was weaker for diesel DFI spray. Whether it is gasoline or diesel, increasing the injection pressure further enhanced the DFI spray to increase the potential of the spray penetration and spray area. However, DFI boosted the spray dispersion under high back pressure conditions but worsened the spray dispersion under low back pressure conditions, especially under flash boiling conditions for gasoline. To a large extent, DFI spray improved spray characteristics and the fuel/air mixture compared to free spray.