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摘要
Premixed tubular flames with different fuels (H(2), CH(4) and C(3)H(8)) mixed with air are investigated using visible laser-induced spontaneous Raman spectroscopy. Two sets of sub-unity Lewis number H(2)/air flames with Phi = 0.175, k = 145-363 s(-1) and Phi = 0.152, k = 127-298 s(-1), respectively, are studied first. The measured temperature and major species profiles show good agreement with numerical simulations using a modified 1-D Oppdif code with the Mueller chemical kinetic mechanism. The measured and predicted extinction strain rates also agree well for all the H(2)/air flarnes with low Reynolds numbers. Two sets of CH(4)/air tubular flames with near unity Lewis number (Phi = 0.54, k = 113-137 s(-1) and Phi = 0.58, k = 166-257 s(-1), respectively) are studied next. Numerical simulations using various chemical kinetic mechanisms are carried out and compared with the measurements. The measured flame temperature is close to its adiabatic value. For the Phi = 0.54 flame at the near-extinction condition (k = 137 s(-1)), the measured peak temperature is higher than the predicted value using the Kee chemical kinetic mechanism. Measured data show a large amount of CO exists in the product zone-under this condition. This suggests that reaction incompleteness is important for the near-extinction flarnes. Improvement of the chemical mechanism is needed to produce an accurate prediction. Raman-derived temperature and species profiles of the premixed above-unity Lewis number C(3)H(8)/air tubular flames at Phi = 0.64, k = 131-203 s(-1) are also studied. The peak flame temperature measured is approximately 15% lower than its adiabatic value. Discrepancies are found between the measurements and simulations with possible explanations given.
- 出版日期2009
