Quantitative Measurements of Chemiluminescence in a Laminar Methane-Air Premixed Flame and Comparison to Numerical Methods

Quantitative measurements of chemiluminescence emissions as a result of CH∗, OH∗, C₂∗, and CO₂∗ were conducted in CH₄/air premixed flames at different equivalence ratios (θ = 0.7-1.33), and numerical results based on one-dimensional flame simulations were compared to these data. A wavelength-dependent and optical-path-corrected emission calibration method was applied to quantify the emission of each excited species. The numerically simulated emission intensities of OH∗ and CH∗ are within the same order of magnitude as the experimental values for the same flame conditions. When self-absorption and cooling water thermosteresis are taken into account, the simulated OH∗ values are 1.0-1.4 times greater than the experimental results, while the CH∗ values are approximately 2.3-4.1 times greater. These findings suggest that more work is required to refine the temperature dependence factors for the CH∗ formation rate coefficients at high temperatures.