Numerical Investigation of Laminar Burning Velocities of High Octane Fuel Blends Containing Ethanol
SAE Technical Paper, (2009)Abstract
Recently, fuels containing ethanol have become more and more important for spark ignition engines. Fuels with up to 10 vol.-% ethanol can be used in most spark ignition engines without technical modification. These fuels have been introduced in many countries already. Alternatively, for fuels with higher amounts of ethanol so called flex fuel vehicles (FFV) exist.
One of the most important quantities characterizing a fuel is the laminar burning velocity. To account for the new fuels with respect to engine design, reliable data need to be existent. Especially for engine simulations, various combustion models have been introduced which rely on the laminar burning velocity as the physical quantity describing the progress of chemical reactions, diffusion, and heat conduction. However, there is very few data available in the literature for fuels containing ethanol, especially at high pressures.
A detailed chemical kinetic mechanism for iso-octane, n-heptane, and ethanol is used to calculate laminar burning velocities under engine relevant conditions. The results are validated against data from literature and new experimental measurements using the closed-vessel bomb method. Finally, based on the results obtained, the effect of ethanol blended to standard fuels is analyzed.