The classical flamelet method, the new Flamelet Generated Manifolds method (FGM), and the hybrid BML/flamelet approach are assessed in the context of the Reynolds-averaged Navier-Stokes (RANS) equations on a large range of configurations for both gaseous and spray flames. The conceptual differences, advantages, and shortcomings of the models are discussed in detail both from a theoretical and a practical point of view.
In order to assess the models under gas turbine like conditions, the reactive flow in TU Darmstadt’s Generic Gas Turbine (GGT), DLR Stuttgart’s PRECCINSTA burner, and a premixed industrial combustor are computed. The computational results are compared to available measurement data and are used to discuss the strengths and the weaknesses of each of the aforementioned combustion models.
In the current study it is shown that the hybrid BML/flamelet method globally performs well, but that it can be difficult to obtain a burning solution with this method, especially when the combustion process is operated close to the flammability limits. While the flamelet method is very robust, it is outperformed by the FGM method even for purely non-premixed configurations. It is demonstrated that the FGM approach can be used for the whole range of combustion modes, from non-premixed over to premixed combustion processes. Since the model did not lead to any difficulties with attaining a burning solution, and is computationally as efficient as the flamelet approach, the authors recommend the usage of this model over the other models investigated.