Abstract
Laminar burning velocities of fuels for advanced combustion engines (FACE-C) gasoline and a surrogate comprising toluene primary reference fuels (TPRFs) were investigated under the effects of exhaust gas recirculation (EGR) dilution and ethanol blending. Measurements were conducted in a spherical constant volume combustion chamber for a range of equivalence ratios from 0.8 to 1.6 at initial temperatures and pressures up to 383 K and 0.6 MPa, respectively. These measurements highlighted the effects of real combustion residuals (using combustion products directly) at mole fractions up to 0.3 and various volumetric percentages of ethanol blending. For both studied fuels, significant reductions in stretched and unstretched flame speeds were observed for mixtures laden with real combustion residuals. Blends with less than 50% ethanol showed barely a minimal enhancement in the flame speed. By combining both EGR and ethanol blending, the flame speed reduction by EGR can be compensated for with ethanol addition. For example, up to 10% of EGR requires 60% ethanol blending to maintain the same flame speed. Flame stability enhancement by EGR addition was also quantified through the determination of the Markstein length.