LASER-INDUCED FLUORESCENCE MEASUREMENTS AND MODELING OF NITRIC-OXIDE FORMATION IN HIGH-PRESSURE FLAMES

We have obtained quantitative LIF measurements of NO concentration in the postflame zone of a series of flat, laminar, premixed C2H6/O-2/N-2 flames at pressures ranging from 3.05 to 14.6 atm. The temperatures o f the flames were 1600-1850 K, indicating that most of the NO produced in the flames is prompt NO, We have found that the equivalence ratio corresponding to the peak NO concentration at a given pressure shifts towards leaner conditions with increasing pressure. In addition, we ha ve modeled the flames using two chemical kinetics models: the Glarborg -Miller-Kee mechanism as modified by Drake and Blint (GMK-DB), and the Miller-Bowman mechanism (MB). Both models accurately predict the pres sure trends of NO formation, while the quantitative agreement with mea surements is, in general, good for the GMK-DB model and poor for the M B model. Explanations are provided both for the poor agreement found w ith the MB model and for the shift in peak NO concentration with press ure.