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Reduction of Hc Emissions By Optimization of the Local Flame Propagation in Multi-Valves SI Engines
Published November 15, 1994 by Societe des Ingenieurs de l'Automobile in France
In order to meet the future HC emission standards for SI engines, the development will be concentrated on the combustion process under unfavorable burning conditions as there are during cold start, transient operation, and combustion of highly diluted mixtures.
Flame quenching is one of the dominant sources for the emission of unburned hydrocarbons in SI engines. Besides the stabilization of combustion, the local optimization of flame propagation significantly influences the reduction of flame quenching effects. Mixture formation and combustion supported by intake generated charge motion (swirl, tumble) and turbulence combined with a detailed tuning of the combustion chamber design provide important means to control flame quenching.
Extensive investigations of combustion behavior were carried out with FEV Fiber Optics technology in order to optimize local flame propagation. The interaction between charge motion, combustion chamber design and flame quenching effects especially under unfavorable burning conditions is discussed.