Analysis of mechanism of ducted fuel injection under non-vaporizing condition

Diesel engines play an important role in road transportation. However, they are facing strict regulations in reducing soot and harmful substances emissions. Ducted fuel injection (DFI) is a new method that effectively attenuates soot on a large scale. How this technology reduces emissions by boosting spray atomization remains unknown. This study focuses on the spray characteristics of DFI, which are difficult to obtain in experimental conditions by using numerical methods. Results showed that DFI increases the spray velocity by the less total entrainment of the ambient gas and the restriction of radial development of the spray. After the jet penetrates the duct, the higher speed leads to higher turbulent kinetic energy, thus enhancing the mixing process of ambient gas and fuel. The analysis of the formation of the mushroom-shaped head was also conducted. This phenomenon is attributed to the influence of pressure difference inside and outside of the duct.