Development of Chemistry-Based Laminar Flame Speed Correlation for Part-Load SI Conditions and Validation in a Research Engine
The detailed study of part-load conditions is essential to characterize engine-out emissions in key operating conditions. The relevance of part-load operation is further emphasized by the recent regulation (e.g. WLTP standard). The combustion development at part-load operations depends on a complex interplay between moderate turbulence levels (low engine speed and tumble ratio), low in-cylinder pressure and temperature and stoichiometric-to-lean mixture quality (to maximize fuel efficiency at partial loads). From a modelling standpoint, the reduced turbulence intensity compared to full-load operations complicates the interaction between different sub-models (e.g. re-consideration of the flamelet hypothesis adopted by common combustion models). In this paper the authors focus on chemistry-based simulations for laminar flame speed of gasoline surrogates at conditions typical of part-load operations.