Flame propagation of mixtures of air with binary liquid fuel mixtures

The laminar flame speeds of mixtures of air with 80% n-dodecane + 20% methylcyclohexane and 80% n-dodecane + 20% toluene, on a per volume basis, were determined in the counterflow configuration over a wide range of equivalence ratio, at atmospheric pressure and 403 K unburned mixture temperature. The choice of the fuel blends was dictated by their anticipated compositions in jet fuels surrogates. Phenomenological analysis shows that the laminar flame speeds of binary fuels mixtures can be estimated using the laminar flame speeds and adiabatic flame temperatures of the neat components. The propagation rates of various binary fuels blends were computed using detailed descriptions of chemical kinetics and molecular transport and were found to be in good agreement with the estimations. Although the fuel initial consumption pathways and the resulting intermediates and radicals may be different for each neat component, the propagation of flames of binary fuels is mostly sensitive to the flame temperature through its influence on the main branching reaction H + O-2 -> OH + O. Thus, kinetic couplings resulting from the presence of two different fuels, appear to have minor effect on flame propagation. (C) 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.