A Proposal of United Combustion Model for Premixed and Diffusion Flames and Its Evaluation (7^th report: Verification of the Combustion Model by A H₂/N₂ Lifted Flame in a Vitiated Coflow)

Abstract

This paper evaluates the accuracy of author's combustion model that can be applied to the premixed and diffusion flames. The proposed united combustion model is based on the author's premixed combustion model and the effect of preferential diffusion is considered through the author's algebra model that evaluates fuel concentration variation on the flame with curvature. In this paper, a H₂/N₂ lifted flame in vitiated coflow conducted by Cabra was numerically simulated. Two simulations were performed, the one is with the proposed preferential diffusion model and the other is without that model. Both of them, calculated mixture fraction profiles were in good agreement with experimental data within x/D≦11 and were not within x/D≧14 because of overestimation of fuel diffusion. Comparing each result, it is indicated that the preferential diffusion model enhanced reaction speed, especially around the jet nozzle exit. However, the influence of overestimation of fuel diffusion is not negligible so that it is difficult to evaluate the superiority of the calculation with the author's preferential diffusion model. As a future works, more suitable analysis object should be simulated for evaluate the preferential diffusion effect quantitatively.