ABSTRACT A nonpremixed methane jet flame was modeled using the flamelet‐generated manifold (FGM) approach in the context of large‐eddy simulation (LES). The effects of radiation and buoyancy were critically examined, and nonpremixed versus premixed tabulation methods were compared. Results demonstrate that incorporating radiation and buoyancy in the FGM significantly improves temperature prediction, which is better validated by experimental results. The FGM results also agree well with the predictions based on the infinitely fast chemistry model in fireFoam. Buoyancy is identified as a more dominant factor than radiation, which enhances the turbulence and the fuel consumption rate, thereby reducing flame height. Furthermore, the laminar nonpremixed counterflow flamelet is established as the superior tabulation method for this case, whereas the premixed tabulation overpredicts the flame height due to differences in species chemistry. It is proposed that accurate FGM predictions for such nonpremixed jet flames require the inclusion of both radiation and buoyancy and the selection of an appropriate flamelet prototype.
Lin et al. (Mon,) studied this question.