In the field of gasoline turbocharged engines, the improvement of combustion efficiency represents a critical point when increased engine torque and reduced fuel consumption are simultaneously expected. Though gasoline port fuel injection is a well known and wide spread technology for fuel delivery in spark-ignition engines, detailed information on the features of the liquid fuel spray and the wall film formation could significantly contribute, in terms of emission control, to the engine development.
In this paper, air-fuel mixture formation and smoke emissions of a turbocharged port-fuel-injected gasoline engine have been investigated by using experimental and numerical analysis techniques. The objective of this activity is to properly choose the injection system and strategy aimed to optimize both engine performance and emission levels.
3-D CFD calculations have been performed in order to deeply investigate the complex phenomena occurring before the combustion process starts. The obtained results have shown a clear relationship between the gasoline wall film accumulation and the engine smoke emission. The numerical results are in good agreement with the experimental data and could provide sound information in the engine development activity and design process.
Both the experimental measurements and the numerical simulations have been carried out at several engine operating points as a function of numerous variables as air charge boost pressure, injection timing, air to fuel ratio, spark advance etc.