Effect of Initial Fuel Temperature on Spray Characteristics of Multicomponent Fuel

Fuel design concept has been proposed for low emission and combustion control in engine systems. In this concept, the multicomponent fuels, which are mixed with a high volatility fuel (gasoline or gaseous fuel components) and a low volatility fuel (gas oil or fuel oil components), are used for artificial control of fuel properties. In addition, these multicomponent fuels can easily lead to flash boiling which promote atomization and vaporization in the spray process. In order to understand atomization and vaporization process of multicomponent fuels in detail, the model for flash boiling spray of multicomponent fuel have been constructed and implemented into KIVA3V rel.2. This model considers the detailed physical properties and evaporation process of multicomponent fuel and the bubble nucleation, growth and disruption in a nozzle orifice and injected fuel droplets. In this study, the results from numerical simulation using this model were compared with experimental data (liquid and vapor distribution and spray tip penetration) which were obtained using a constant volume vessel. It was confirmed that high volatility fuel vaporized earlier than low volatility fuel and high vapor concentration region of high volatility fuel was located in the upstream of the spray, as well as the numerical results. The spray tip penetration obtained from numerical simulation also showed good agreement with the experimental results. In addition, the effect of flash-boiling on the spray characteristics of multicomponent fuel was verified by changing the initial fuel temperature using numerical simulation. As a result, flash-boiling rapidly vaporized both fuel components due to the appearance of bubbles in nozzle orifice and injected fuel droplets.