QUANTITATIVE LIF MEASUREMENTS AND MODELING OF NITRIC-OXIDE IN HIGH-PRESSURE C2H4 O-2/N-2 FLAMES/

We have obtained quantitative LIF measurements of NO concentration in the post-flame zone of a series of flat, laminar, premixed C2H4/O-2/N- 2 flames at pressures ranging from 1 to 11.9 atm. The internal consist ency of the data was verified by demonstrating good agreement between measurements based on two different NO excitation lines. The temperatu res of the flames were 1600-1850 K, indicating that most of the NO pro duced in the flames is prompt-NO. The results show that the equivalenc e ratio corresponding to the peak NO concentration at a given pressure shifts towards leaner conditions with increasing pressure. We have al so modeled the flames using two chemical kinetics schemes: (1) the Gla rborg-Miller-Kee mechanism as modified by Drake and Blint (GMK-DB), an d (2) the Miller-Melius hydrocarbon mechanism, combined with the nitro gen kinetics of Drake and Blint (MIME-DB). Both models are qualitative ly inaccurate with respect to the measured pressure shift, particularl y at pressures below 6.1 atm. Both models also tend to underpredict th e NO concentrations, although the GMK-DB model is acceptable in many c ases.