Effect of fuel type on equivalence ratio measurements using chemiluminescence in premixed flames

Local temporally-resolved measurements of chemiluminescent intensity from OH*, CH* and C-2(*) radicals were obtained in premixed counterflow flames operating with propane and prevaporised fuels (isooctane, ethanol and methanol), for different equivalence ratios and strain rates. The results quantified independently the effects of fuel type, strain rate and equivalence ratio on chemiluminescent emissions from flames. The ability of chemiluminescent intensity from OH*. CH* and C radicals to indicate heat release rate depends strongly on fuel type. The intensity ratio OH*/CH* has a monotonic decrease with equivalence ratio for all fuels and can be used to measure equivalence ratio of the reacting mixture. For propane and isooctane, the OH*/CH* ratio remains independent of flame strain rate, whereas some dependence is observed for ethanol and methanol. (C) 2010 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.