Quantitative LIF measurements and modeling of nitric oxide in high-pressure C2H4/O2/N2 flames

We have obtained quantitative LIF measurements of NO concentration in the post-flame zone of a series of flat, laminar, premixed C2H4/O2/N2 flames at pressures ranging from 1 to 11.9 atm. The internal consistency of the data was verified by demonstrating good agreement between measurements based on two different NO excitation lines. The temperatures of the flames were 1600–1850 K, indicating that most of the NO produced in the flames is prompt-NO. The results show that the equivalence ratio corresponding to the peak NO concentration at a given pressure shifts towards leaner conditions with increasing pressure. We have also modeled the flames using two chemical kinetics schemes: (1) the Glarborg-Miller-Kee mechanism as modified by Drake and Blint (GMK-DB), and (2) the Miller-Melius hydrocarbon mechanism, combined with the nitrogen kinetics of Drake and Blint (MIME-DB). Both models are qualitatively inaccurate with respect to the measured pressure shift, particularly at pressures below 6.1 atm. Both models also tend to underpredict the NO concentrations, although the GMK-DB model is acceptable in many cases.