Temperature measurement in fuel-rich non-sooting low-pressure hydrocarbon flames

Several temperature measurement techniques were compared for the investigation of fuel-rich, premixed, flat, low-pressure flames of propene, acetylene, and cyclopentene with maximum temperatures around 2400 K. Vibrational Stokes/anti-Stokes Raman measurements with a KrF excimer laser using CO, H₂, and H₂O as temperature indicators were examined at 50 and 200 mbar for different flame stoichiometries. Also, laser-induced fluorescence (LIF) of OH in the A-X band was used, and complementary lifetime measurements were performed to account for a variation of fluorescence quantum yield with rotational quantum number. LIF using seeded NO (0.2-1.0%) was applied both in point-wise and 1D temperature measurement in spite of the anticipated interaction of NO with the fuel-rich flame chemistry. Furthermore, thermocouple measurements were performed in the preheat zone. These techniques were compared with respect to accuracy and the potential for routine applications under fuel-rich low-pressure conditions.