High-Fidelity Multi-Regime Combustion Modelling for EGR-Operated Gas Turbines

This thesis addresses high-fidelity CFD modelling of multi-regime combustion in gas turbines operating under high exhaust gas recirculation (EGR) conditions, developed within the EU Horizon Europe TRANSITION project. The work makes three key contributions: (1) numerical support of advanced burner design through lean-blowout (LBO) analyses under CO₂-diluted air conditions, enabled by a validated extended Flamelet Generated Manifold (FGM) formulation; (2) development and implementation of an analytically reduced chemistry (ARC) mechanism for natural gas/hydrogen blends in ANSYS Fluent, including novel QSS capabilities; and (3) a hybrid LES framework coupling the Thickened Flame model in premixed regions with Fine-Scales turbulence–chemistry interaction closures in non-premixed regions, validated on the Sandia D flame and applied to the TRANSITION baseline burner. The thesis advances cost-aware, high-fidelity simulation strategies for next-generation gas turbine combustors operating under challenging EGR and fuel-flexibility conditions.