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Carbon fiber reinforced carbon (CFRC) composites possess high specific strength, without loss of strength at high temperatures. The fiber architecture of these composites can be manipulated to yield tailored mechanical and thermal properties. Because of their light weight and the above attributes, these composites are attractive for pistons and other reciprocating parts in internal combustion engines. However, few tests have been performed to test these pistons for structural integrity and engine performance. Testing was undertaken to assess the basic suitability of this material for use in a spark-ignition engine. Of particular were basic mechanical function and combustion effects. With the CFRC piston cylinder, hydrocarbon emissions were higher, IMEP lower and the higher piston temperature induced detonation prematurely. The increase in hydrocarbon emissions was attributed to higher crevice volumes under hot operating conditions and fuel adsorption/desorption into the piston crown.

An overview of work relating to the investigation of direct injection gasoline engines is presented. Comparisons between conventional port-injected and two separate gasoline direct injection combustion systems are drawn. The comparison is between two of the main alternative GDI systems currently under consideration, reverse tumble charge motion with high-pressure swirl-type fuel injector (RTGDI) and low-pressure air-assist direct injection (AAGDI). This comparison was carried out using a 444cc single cylinder research engine of Cosworth Technology design. Included in the discussion are the influence of GDI systems on volumetric efficiency and performance at full load and fuel efficiency and emissions at part load. Techniques to aid the development and calibration of GDI systems are discussed, including Moving Geometry CFD analysis and Design of Experiments (DOE).

A study of the fundamental design characteristics of SI engine inlet ports is presented. The work involved the parameterisation of inlet port design features to enable a simplified description of the fundamental form of a port to be made. A parametrically controlled CAD model was then created to enable variations in port geometry to be generated quickly and surface meshes created for CFD analysis. CFD analysis and Design of Experiments were employed to establish the relationship between design parameters and port flow characteristics. Correlation of the CFD results was established via the use of a number of rapid prototype port models, tested on a flow bench. To aid interpretation of the data, a computer emulation of the results with a Graphical User Interface (GUI) was produced using MATLAB software. The resultant GUI is available for use as a tool to highlight the effects of key design parameters during the concept and optimisation stages of inlet port design.

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.