Particulates in GDI and their relation to wall-film and mixing quality
2022-01-0517
03/29/2022
- Event
- Content
- Particulates from GDI engines are inevitable, but can be kept low by means of various approaches such as high injection pressures, optimization of the spray formation, injection timing etc. It is known that liquid wall film on the piston and mixing are key factors influencing directly or indirectly the formation of particulates. It is almost impossible to completely avoid that the fuel spray impinges on the piston regardless of fuel injection timing which means that non-evaporated fuel can remain on the piston until late in the compression stroke or even further leading to increases in PN caused by pool-fires or rich zones. For a given fuel pressure, the timing of the fuel injection, SOI, is the most influencing factor. In this paper particulates data in numbers and sizes from experiments in single cylinder research engine are presented and used together with data of wall film and mixing quality from CFD simulations for sweeps in SOI timing. How the SOI sweeps were carried out in the experiments was also carefully considered to maximize data repeatability. The data was analyzed and SOI sweeps were re-ordered due to its air fuel cylinder uniformity index calculated from CFD to assess possible correlations between PN and mixing. Wall film was also analyzed from the CFD simulations using a surrogate fuel with a vaporization characteristic similar to real Gasoline to analyze its influence on PN. Fuel escape to the manifold which is always present in GDI to some degrees were also quantified for various SOI.
- Citation
- Dahlander, P., Babayev, R., Ravi Kumar, S., Etikyala, S. et al., "Particulates in GDI and their relation to wall-film and mixing quality ," SAE Technical Paper 2022-01-0517, 2022, .