Steady flamelet modeling of a non-premixed turbulent CH4/H2/N2-air flame with and without radiation

Diego Luis Deon¹; Fernando Marcelo Pereira¹

¹ Federal University of Rio Grande do Sul

doi:10.20906/CPS/COB-2015-0642

Resumo

A non-premixed turbulent CH4/H2/N2 flame, surrounded by a low-velocity air coflow, is numerically reproduced employing the steady laminar flamelet concept. In this technique, the mean reactive scalars, i.e., temperature and species mass fractions, are obtained from the solution of quasi-unidimensional counter-flow flames, named flamelets. The results are stored in a databank, parameterized by mixture fraction, its variance and dissipation rate. To generate the flamelet library, the turbulence-chemistry interaction is taken into account through presumed probability density functions of these mean scalars. Thus, to solve the complete flow problem, there is no need to deal with the highly coupled energy and species partial differential equations, since their mean values are recovered from the flamelet library, reducing drastically the computational time required to achieve results convergence. The flame under investigation is widely exploited, being the target from several numerical approaches. The numerical results are compared to the experimental ones, in order to show the agreement level to measurements and the ones obtained by other researchers. The predicted quantities have shown to be in reasonable agreement with experimental data, for longitudinal velocity, mixture fraction, temperature and species mass fractions. However, some discrepancies exist, like in NO predictions, what is presumed to be due to some simplifications present in the model.

Palavras-chave: steady laminar flamelet model; non-premixed flame; turbulent combustion; Flame DLR-A