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Technical Paper

Lubricant Induced Pre-Ignition in an Optical SI Engine

2014-04-01
2014-01-1222
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.
Technical Paper

CO2 Emission Reduction Synergies of Advanced Engine Design and Fuel Octane Number

2014-10-13
2014-01-2610
Engine downsizing is a key approach employed by many vehicle manufacturers to help meet fleet average CO2 emissions targets. With gasoline engines in particular reducing engine swept volume while increasing specific output via technologies such as turbocharging, direct injection (DI) and variable valve timing can significantly reduce frictional and pumping losses in engine operating areas commonly encountered in legislative drive cycles. These engines have increased susceptibility to abnormal combustion phenomena such as knock due to the high brake mean effective pressures which they generate. This ultimately limits fuel efficiency benefits by demanding use of a lower geometric compression ratio and sub-optimal late combustion phasing at the higher specific loads experienced by these engines.
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