COMPARISON OF REDUCED AND FULL CHEMICAL MECHANISMS FOR NONPREMIXED TURBULENT H-2-AIR JET FLAMES

Use of reduced chemical mechanisms in combustion applications is becom ing standard practice due to the reduced computational effort involved in simulating finite rate chemistry. Reduced mechanisms are developed with simplifying assumptions which limit the phenomena that can be st udied. In this study, a comparison between a full, finite rate, chemic al mechanism and a standard reduced mechanism for H-2-air combustion a nd NO formation is made for nonpremixed, turbulent jet flames. The num erical simulations incorporate an innovative mixing model so that turb ulent-chemistry interactions can accurately be captured enabling a cri tical evaluation of the assumptions made in the reduced mechanism. Res ults indicate that the reduced mechanism and the full mechanism with d ifferential diffusion and variable Lewis number compare relatively wel l except for the radical species. NO emission index results also compa re favorably even though substantial variations in Lewis number and di fferential diffusion effects are found to exist in the full mechanism results.