For some time, spatial nonuniformities in the unburned mixture within a spark ignition engine have been suspected of contributing to cycle-by-cycle variations in combustion. In this work, an experimental structure was developed that allowed the effects of fuel/air nonuniformity and residual gas/fresh charge nonuniformity to be separately addressed, with special regard given to their impact on the flame development process and combustion rate. Under the conditions of light loads and low speed, it was found that a decrease in fuel-air nonuniformity caused a slight reduction in the variation of the early flame development angle but had no significant impact on the statistics of the main combustion phase or IMEP. Eliminating residual gas nonuniformity by skip firing the engine and adding equivalent residual to the fresh mixture prior to entry to the cylinder had no detectable impact on the flame development process. In fact all evidence showed that the in-cylinder residual gas present under the continuous-firing conditions tested was well mixed with the fresh charge by the time of spark discharge.
Mixture Nonuniformity Effects on S.I. Engine Combustion Variability
Sae Technical Papers
International Fuels & Lubricants Meeting & Exposition ; 1990
1990-10-01
Conference paper
English
Mixture nonuniformity effects on S.I. engine combustion variability
Automotive engineering | 1990
|Mixture preparation and combustion variability in a spray-guided DISI engine
Automotive engineering | 2007
|Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine
SAE Technical Papers | 2007
|Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine
British Library Conference Proceedings | 2007
|