Analysis on Impacts of Wall Hole on Spray Macroscopic Characteristics of Ducted Fuel Injection under Evaporating Conditions

To investigate the effect of duct wall on spray and explore the optimal duct configuration, the present study employed closed wall and porous wall duct to investigate the macroscopic characteristics of spray field of ducted fuel injection (DFI) under evaporating conditions. The experimental results validated the adopted simulation model, providing a prerequisite for the study of the spray characteristics. The results showed that the duct has the effect of slowing down the spray momentum loss, but the mass exchange between the spray inside the duct and the outside ambient gas through the wall hole weakens this effect, resulting in the axial velocity of DFI spray with the closed wall duct being greater than that with the porous wall duct. The pumping effect caused by the significant pressure difference inside and outside the duct greatly promotes gas entrainment at the duct inlet, while the spray-ambient gas interaction through the wall hole weakens this gas entrainment. The duct has a cooling effect on the spray, but the temperature exchange between the spray inside the duct and the outside ambient gas through the wall hole weakens this effect.