Optical Investigation of a Partial Fuel Stratification Strategy to Stabilize Overall Lean Operation of a DISI Engine Fueled with Gasoline and E30

This paper offers new insights into a partial fuel stratification (PFS) combustion strategy that has proven to be effective at stabilizing overall lean in direct injection spark ignition engines. To this aim, high spatial and temporal resolution optical diagnostics were applied an optically accessible engine working PFS mode for two fuels different durations of pilot the time spark: 210 µs 330 E30 (gasoline blended with ethanol by 30% volume fraction) gasoline, respectively. In both conditions, early injections during intake stroke used generate well-mixed background. The results compared rich, stoichiometric timings. process, it was possible detect non-spherical highly wrinkled blue flame, coupled yellow diffusive flames due rich zones near plug. initial flame spread cases faster any (lean, rich), suggesting propagation is enhanced enrichment local turbulence caused injection. Different spray evolutions found strongly influence kernel inception propagation. showed some differences terms shapes front extension flames. Yet, repeatable.