Development of gasoline-ethanol blends laminar flame speed correlations at full-load Si engine conditions via 1D simulations

Abstract

Nowadays, most of the engineering development in the field of Spark-Ignited (SI) Internal Combustion Engines (ICEs) is supported by 3D-CFD simulations relying on flamelet combustion models. Such kind of models require laminar flame speed as an input to be specified by the user. While several laminar flame speed correlations are available in literature, for gasoline and pure ethanol at ambient conditions, there is a lack of correlations describing laminar flame speed of gasoline-ethanol blends, for different ethanol volume content, at conditions deemed to be representative of engine-like conditions. Toluene Reference Fuel surrogates with addition of ethanol (ETRF), suitable for representing gasoline-ethanol blends up to 85% vol. ethanol content are formulated. Thanks to these surrogates, 1D premixed laminar flame speed calculations are performed at selected engine-relevant conditions for a E5, E20 and E85 fuels. As a final outcome, three different laminar flame speed correlations based on the chemistry-based calculations are derived for E5, E20 and E85 gasoline-ethanol fuel blends focusing on typical full-load engine conditions. Such kind of correlations can be easily implemented in any 3D-CFD code to provide a chemistry-grounded estimation of laminar flame speed during combustion calculations. Such correlations are of practical use, since they might help in developing the next generation of bio-fuels powered internal combustion engines.