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The experimental work was concerned with improving understanding of the competing effects of the latent heat of vaporization and auto-ignition delay times of different ethanol blended fuels during heaving knocking combustion. The unique single cylinder SI engine employed included full bore overhead optical access capable of withstanding unusually high in-cylinder pressures. Heavy knock was deliberately induced under moderate loads using inlet air heating and a primary reference fuel blend of reduced octane rating. High-speed chemiluminescence imaging and simultaneous in-cylinder pressure data measurement were used to evaluate the combustion events. Under normal operation the engine was operated under port fuel injection with a stoichiometric air-fuel mixture. Multiple centered auto-ignition events were regularly observed, with knock intensities of up to ~40bar. Additional excess fuel of varied blend was then introduced directly into the end-gas in short transient bursts.

This work is concerned with the analysis of different charge dilution strategies employed with the intention of inhibiting knock in a high output turbocharged gasoline engine. The dilution approaches considered include excess fuel, excess air and cooled external exhaust gas re-circulation (stoichiometric fuelling). Analysis was performed using a quasi-dimensional combustion model which was implemented in GT-Power as a user-defined routine. This model has been developed to provide a means of correctly predicting trends in engine performance over a range of operating conditions and providing insight into the combustion phenomena controlling these trends. From the modelling and experimental data presented, it would appear that the use of cooled externally re-circulated exhaust gases allowed fuel savings near to those achieved via excess air, but with improved combustion stability and combustion phasing closer to the optimum position.

This work was concerned with study of lubricant introduced directly into the combustion chamber and its effect on pre-ignition and combustion in an optically accessed single-cylinder spark ignition engine. The research engine had been designed to incorporate full bore overhead optical access capable of withstanding peak in-cylinder pressures of up to 150bar. An experiment was designed where a fully formulated synthetic lubricant was deliberately introduced through a specially modified direct fuel injector to target the exhaust area of the bore. Optical imaging was performed via natural light emission, with the events recorded at 6000 frames per second. Two port injected fuels were evaluated including a baseline commercial grade gasoline and low octane gasoline/n-heptane blend. The images revealed the location of deflagration sites consistently initiating from the lubricant itself.