Determination of and fuel structure effects on laminar flame speeds of C1 to C8 hydrocarbons

Laminar flame speeds determined by using the counterflow twin flame configuration were compared for various C-1 to C-8 hydrocarbons, including alkanes, alkenes, alkynes, aromatics, and alcohols. The data were compared over an extensive range of equivalence ratios at room temperature and atmospheric pressure. The comparison shows that the laminar flame speeds of normal alkanes are close throughout the entire range of equivalence ratios studied, except for methane whose flame speeds are consistently lower. The more unsaturated the molecule the higher the flame speed for fuels having the same carbon number in the order of alkanes < alkenes < alkynes. Methyl substitution for hydrogen or branching reduces the flame speeds for both alkanes and alkenes. The flame speeds of large saturated cyclic species (cyclohexane and cyclopentane) are close to those of their normal alkane analogs.