Combustion characteristics of ethanol and PRF laminar flames

Abstract

In this study, laminar burning velocities of ethanol, iso-octane and n-heptane-air mixtures were determined experimentally over a wide range of equivalence ratio under the various pressures up to 0.5MPa, employing spherically expanding flames. Considering non-linear extrapolations, the effects of stretch was minimized by extrapolating the reference flame speed to vanishing stretch. The laminar burning velocities of iso-octane were found to be lower than those of ethanol and n-heptane throughout the range of experimental equivalence ratios. For all fuels, laminar burning velocities were found to decrease with increase initial pressure. From schlieren images, ethanol, iso-octane and n-heptane-air mixtures on the fuel rich region were found to become unstable at 0.1MPa. For all fuels, increasing initial pressure was found to get flame more unstable and narrow the stable flame region. © 2012 The Japan Society of Mechanical Engineers.