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Experimental studies on controlled auto-ignition (CAI) combustion in a 4-stroke gasoline engine
Published February 01, 2000 by Institution of Mechanical Engineers in United Kingdom
This paper presents results from an experimental program researching the in-cylinder conditions necessary to obtain Controlled Auto-Ignition (CAI) combustion in a 4-stroke gasoline engine. A single-cylinder, variable compression ratio research engine is used for all experiments. Investigations concentrate on establishing the CAI operating range with regard to Air/Fuel ratio and Exhaust Gas Recirculation (EGR) and their effect on ignition timing, combustion rate and variability, ISFC, and engine-out emissions such as NOx, CO, and unburned HC. Fuels of different octane numbers are tested. The range of successful CAI operation (Air/Fuel ratio and EGR rate) is shown for each fuel. In relevant cases, these results are compared to those obtained during normal spark-ignition operation so that the benefits of CAI combustion can be more fully appreciated.