Measurements and Modeling of OH and NO in Premixed C2H6/O2/N2 Flames at Atmospheric Pressure

Abstract

We present laser-induced fluorescence (LIF) measurements of OH and NO concentrations in six premixed, atmospheric-pressure, laminar, flat C2H6/O2/N2 flames. The flames have a similar dilution ratio and total flow rate, while the equivalence ratios vary between 0.6 and 1.6. Using the data, we evaluate the predictions from two chemical kinetics models. These two models are the Glarborg, Miller, and Kee mechanism as modified by Drake and Blint (GMK-DB) and the GRI-Mech mechanism, version 2.11 (GRI). Two temperature profiles are used to generate the predictions from each model: a measured temperature profile and a predicted profile based on the energy equation. For the GMK-DB model, the measured temperature profile tends to give better results than the calculated temperature profile for the OH concentrations. Both the NO and OH concentration profiles are well predicted by the GMK-DB model in lean flames, while poorer agreement is generally obtained between measurements and modeling in the rich flames. The predictions for the GRI mechanism are satisfactory for both OH and NO in the lean flames but also become poorer in the richer flames. The two temperature profiles do not give significantly different results when using the GRI model in lean flames, but in rich flames, the measured temperature profile tends to give better agreement with the LIF measurements. The results indicate that while improved temperature measurements would be beneficial, further refinement of the chemical kinetics is required to improve the agreement between the predicted NO and OH concentration profiles in the rich flames. In particular, it is important that the rate coefficient for the reaction CH + N2 ↔ HCN + N be more firmly established.