Experimental and numerical study of OH* chemiluminescence in hydrogen diffusion flames

Experimental and numerical study of OH* chemiluminescence in hydrogen diffusion flames

A co-flow burner was designed to generate axisymmetric diffusion flames for the application of line-of- sight optical diagnostics to hydrogen flames. Chemiluminescence images of OH∗ from laminar hydrogen diffusion flames, with and without co-flowing air, were recorded using an intensified camera system with a narrow-band filter at approximately 310 nm. The spectra of OH∗ chemiluminescence was acquired by a separate optical system. Local concentrations of the radiating radical OH∗ were determined using the inverse Abel transformation and calibration against a light source of known radiance. The uncertainty of the OH∗ concentration measurements is analysed to be −22% to +12% in the current experimental configuration. Numerical reconstruction of the physical flames was performed using a two dimensional axisymmetric flow model coupled with a detailed H 2 /O 2 oxidation chemistry mechanism and an OH∗ chemiluminescent sub-scheme which includes options to use 6 different rate coefficients recommended in the literature for the OH∗ formation reaction H + O + M OH∗ + M (R1). The numerical simulations using the rate coefficient of 1.5 ×10 13 exp (−5 . 98 kcal mol −1 / RT) cm 6 mol −2 s −1 for R1 demonstrate the best agreement with the measured OH∗ chemiluminescence.

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