Effect of fuel film deposition on combustion process in PFI SI engine

The present paper discusses the experimental investigations on the flame induced by fuel film deposition ignition in a single cylinder, ported fuel injection, four-stroke, over-boosted spark-ignition engine with a four-valve production head. The engine was optically accessible and equipped with a transparent quartz window in the bottom of the combustion chamber. 2D-digital imaging and UV-visible natural emission spectroscopy were used to follow the flame propagation in the combustion chamber. Two colour pyrometers were applied to evaluate flame temperature and soot concentration. Particulate matter and soot primary particles diameters were measured and correlated with the soot amount produced in the combustion chamber. The effect of the intake air pressure and injection phasing was investigated. Optical setup for spectroscopic measurements and visible digital imaging, visible flame emission detected in the chamber for the selected operating conditions, visible emission spectra measured at 60 CAD ASOS in the chamber, soot concentration measured at the selected operating conditions, integral soot concentration measured at the selected operating conditions, particulate mass concentration measured by the Opacimeter and particles number concentration measured by LII at the engine exhaust are presented in the paper.