STUDY OF RADIATIVE EFFECTS ON LAMINAR COUNTERFLOW H-2 O-2/N-2 DIFFUSION FLAMES/

The effects of radiative transfer on the structure and extinction limi ts of counterflow H-2/O-2/N-2 diffusion flames are studied numerically using detailed kinetics and transport properties. The radiative prope rties of the main emitting species, H2O and OH in these flames, are re presented using a statistical narrow-band model. The radiative transfe r equation and flow governing equations are solved in a coupled manner . The model is first validated by comparing numerical results with Ray leigh temperature and total flame radiative emission measurements. It is then applied to the numerical study of radiative effects on flame s tructure and properties. These effects, i.e., a decrease in flame temp erature, flame width and production of minor species, are found to be the most important for high values of inlet H-2 mass fraction and for low strain rates. Quantitative values of radiative low strain rate ext inction limits are given. The limits of validity and the discrepancies due to the optically thin medium approximation are also investigated.