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An experimental study has been carried out on the multiple fuel injection process and its effect on the mixing and combustion in a single cylinder diesel engine with optical access. The engine is equipped with a production type cylinder head and a high pressure common rail fuel system which comprises a directly driven high pressure fuel pump and a control system capable of 8 injections per stroke. The single cylinder optical engine could be operated lubrication-free for up to 5 minutes due to the application of special coating on the piston liner and careful design of the piston and extended cylinder block. The in-cylinder spray and combustion were visualized at 10,000 fps by a high-speed colour video camera and a copper vapour laser. The high-speed video recordings and in-cylinder pressure and heat release analysis for up to four fuel injections will be presented and discussed.

Over the last decade, the high speed direct injection (HSDI) diesel engine has made dramatic progress in both its performance and market share in the light duty vehicle market. However, with ever more stringent emission legislation to be introduced over coming years, the simultaneous reduction of NOx and Particulate Matter (PM) from the HSDI diesel engine is being intensively researched. As part of a European Union (EU) NICE integrated project, research has been carried out to investigate the fuel injection and combustion from a narrow cone fuel injector in a high speed direct injection single cylinder engine with optical access utilising a multiple injection strategy and various alternate fuels. The fuel injection process was visualised using a high speed imaging system comprising a copper vapour laser and a high speed video camera. The auto-ignition and combustion process was analysed through the chemiluminescence images of CHO and OH using an intensified CCD camera.

A fuel fractionating system is designed and commissioned to separate standard gasoline fuel into two components by evaporation. The system is installed on a Ricardo E6 single cylinder research engine for testing purposes. Laboratory tests are carried out to determine the Research Octane Number (RON) and Motoring Octane Number (MON) of both fuel fractions. Further tests are carried out to characterize Spark-Ignition (SI) and Controlled Auto-Ignition (CAI) combustion under borderline knock conditions, and these are related to results from some primary reference fuels. SI results indicate that an increase in compression ratio of up to 1.0 may be achieved, along with better charge ignitability if this system is used with a stratified charge combustion regime. CAI results show that the two fuels exhibit similar knock-resistances over a range of operating conditions.