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The transport of fuel droplets into the combustion chamber of an SI engine and their subsequent evaporation has been studied, using a new optical diagnostic technique, Interferometric Laser Imaging for Droplet Sizing (ILIDS), which allows temporally and spatially resolved measurements of droplet size distributions. The measurement technique and its application to in-cylinder engine measurements are described. Measurements were made under warmed-up conditions, with open valve injection timing, in a Ricardo Hydra single cylinder engine. The results showed differences in the evolution of the droplet size distribution in cylinder with variations in load and speed. At 1200 rpm under full load, droplets arrived quickly into the cylinder, and were small, the Sauter Mean Diameter (SMD) being in the region 10-12 μm on arrival, so that mixture preparation was good.

The development of fuels for Formula One engines is described by reference to the 1988 - 1992 Grand Prix seasons. Fuel development for both turbo-charged and normally aspirated engines is detailed, and a robust methodology is presented which enables sustainable fuel performance improvements by optimised matching to the engine combustion system. The relevance of Formula One fuel research to commercial gasolines is described. It is shown that there are many areas of research where there are benefits arising that are directly transferable to the motoring public.

An investigation has been carried out to compare the ability of swirling and tumbling flow regimes to enhance the turbulence in a disc-shaped gasoline combustion chamber. Scanning LDA measurements have been made of spatial velocity fluctuations in a high swirl, a tumble and a baseline low swirl build. All of the testwork was carried out under motored conditions at an engine speed of 1200 rev/min. A parametric model has been developed to account for the effects of mean flow cyclic variation and system noise. It is shown that the model fits very well to the experimental data, enabling unbiased estimates of turbulence intensity and turbulence length scale to be made. In the region measured around TDC the high swirl build achieves a uniform increase in turbulence Intensity of about 55% over the baseline build. The tumble build however achieves a peak in turbulence intensity of more than twice the baseline build at 30° BTDC.