Cycle-by-Cycle Variations in Combustion and Mixture Concentration in the Vicinityof Spark Plug Gap

摘要

The correlations between IMEP and pressures at referenced crank angles havedifferent trends for different equivalenoe ratios. A fiber optic spark plug was used to detect the initial flame development which was then used to analyze the combustion cyclic variation. Rayleigh scattering measurements were applied to detect the air-fuel mixture fluctuations in the vicinity of spark plug gap for both homogeneous and inhomogeneous mixture preparations in a spark ignition engine. The variation in mixture concentration in the vicinity of spark plug gap was not confirmed as a major contributor to cycle-by-cycle variation in combustion for any of the homogeneous mixture cases or for the stoichiometric and lean mixtures of port injection. However, a leaner mixture of port injection did correlate with the cyclic variation in combustion. (AN).