Fuel-rich propene and acetylene flames: A comparison of their flame chemistries

Laminar premixed flat propene and acetylene flames with different C/O ratio s have been investigated at 50 mbar. Profiles of a variety of stable and ra dical species were obtained by molecular beam sampling mass spectrometry (M BMS). The temperature profiles were measured with laser-induced fluorescenc e (LIF) of OH and NO. In the high-temperature regime, the OH radical was pr obed, whereas NO was added to the fresh gases as a temperature indicator fo r the cooler regions. In evaluating the measurements, emphasis was laid on the formation of C-6 species, in particular of C6H6, as one of the key spec ies in soot formation. Concentration profiles for more than 30 species have been analyzed, and the observed differences in the concentrations of sever al intermediates, in particular potential precursors of benzene, are discus sed. A reaction how analysis has been performed to reveal that striking dif ferences exist in the chemistry of fuel-rich propene and acetylene flames, a result which is of value for flame modeling. For the flames investigated, the observed differences in the concentration profiles of some potential p recursors of benzene are discussed in comparison with the predictions of fl ame modeling. (C) 2000 by The Combustion Institute.