High-Speed Photography and Image Analysis Techniques Applied to Study Droplet Motion within the Porting and Cylinder of a 4-Valve SI Engine

High-speed cine photography has been applied to an optically-accessed version of a modern 4-valve, pent-roof, si engine in order to observe the behaviour of fuel under cold starting and warm-up conditions.

A wall film was formed on the combustion chamber surface in the vicinity of the valves when fuel was supplied by pintle and disk-type injectors. This wall film survived combustion but was drawn into the exhaust system when the exhaust valves opened. The use of an air-blast atomiser avoided the formation of this wall film, but some wetting of the piston was apparent, as it was with the other types of injector.