COMBUSTION MODELLING OF THE T100 MICRO-GAS TURBINE BURNER INCLUDING THE INFLUENCE OF THE STRETCH AND HEAT LOSS/GAIN EFFECTS ON THE FLAME

This paper focuses on the application of an extension for Zimont’s Turbulent Flame Closure (TFC) model turbulent flame speed formulation to include stretch and heat loss and gain effects on the flame. The effects are introduced, by tabulating the consumption speed of laminar 1D counter-flow flames in a”fresh-to-burnt” configuration for different stretch and heat loss/gain values. The consumption speed look-up table is then used to compute the flame turbulent flame speed within the tabulated-chemistry Flamelet Generated Manifolds (FGM) combustion model. Existing models, such as the Extended Turbulent Flame Closure (ExtTFC), are able to account for stretch and heat loss effects downstream of the reaction zone. A new model, named ExtTFCcomplete, is presented taking into account, in the construction of the consumption speed look-up table, the heat loss and gain effects both on the combustion products and reactants. The necessity of evaluating the heat loss/gain effects on the reactants derives from the flow and geometrical characteristics of the Ansaldo Green Tech AE-T100 micro-gas turbine (mGT) burner, the object of this study. The reverse-flow inlet air and the main line fuel distribution plenum geometry demand to consider the heat loss/gain effects on the mixture before entering the combustion chamber to correctly catch the flame characteristics. In a first step, the performances of the proposed model are validated by comparing computational fluid dynamics (CFD) simulations predictions to experimental data of an atmospheric turbulent premixed bluff-body stabilized CH4/air flame. The model is then numerically applied to the AE-T100 burner, emphasizing how the extension significantly improves the flame shape prediction with respect to the original Zimont model.