An Open Cycle Simulation of DI Diesel Engine Flow Field Effect on Spray Processes

Clean diesel engines are one of the fuel efficient and low emission engines of interest in the automotive industry. The combustion chamber flow field and its effect on fuel spray characteristics plays an important role in improving the efficiency and reducing the pollutant emission in a direct injection diesel engine, in terms of influencing processes of breakup, evaporation mixture formation, ignition, combustion and pollutant formation. Ultra-high injection pressure fuel sprays have benefits in jet atomization, penetration and air entrainment, which promote better fuel-air mixture and combustion. CFD modeling is a valuable tool to acquire detailed information about these important processes. In this research, the characteristics of ultra-high injection pressure diesel fuel sprays are simulated and validated in a quiescent constant volume chamber. A profile function is utilized in order to apply variable velocity and mass flow rate at the nozzle exit. The CFD model is also applied to an open cycle engine model to study the effects of engine flow field features such as swirl and tumble motions on the spray behavior. In particular, the effect of the above mentioned parameters on spray penetration Sauter mean diameter (SMD) and fuel distribution in the chamber are extensively discussed.