Large-eddy simulation on the effect of fuel injection pressure on the gasoline spray characteristics 2019-01-0060
Increasing gasoline injection pressure has a substantial potential to reduce emissions while maintaining the advantage of the high efficiency of spark ignition engine. Present gasoline injectors are operating in the range of 200 to 250 bar, there is an interest in injection pressures of 400 bar, 600 bar and even higher for further emissions reduction and fuel efficiency improvements. A fundamental understanding of gasoline spray characteristics is vital to gain the insight of spray behavior under ultra-high injection pressure. The better understandings also essential to improve model development and facilitate the integration of advanced injection system with elevated injection pressure into future gasoline engines. It is therefore critical to model the high injection pressure gasoline spray using state-of-the-art computational fluid dynamics (CFD) methods with high time and space accuracy.
In the present study, a gasoline spray characteristics were investigated over a varied fuel injection pressure range between 20 to 150 MPa. The numerical calculations were performed in an constant volume chamber under the non-vaporising conditions using well known Eulerian-Lagrangian spray simulation model. The numerical model utilized an large-eddy simulation (LES) approach for the gas flow and a standard Lagrangian spray model for the liquid phase. The atomization was described using combined primary and secondary atomization sub-models. The liquid penetration length was accurately compared to experimental finding under the different fuel injection pressure. The arithmetic mean droplet diameters (D10) and sauter mean droplet diameters (D32) as a function of time were compared with the measured droplet diameters. The droplets size distribution over the time was also presented. The results indicated that high fuel injection pressure increased the liquid penetration length and significantly reduce the droplet size.
Sandip Wadekar, Akichika Yamaguchi, Michael Oevermann
Chalmers University of Technology, Denso Sweden
International Powertrains, Fuels & Lubricants Meeting