ASSESSMENT OF FLAMELET GENERATED MANIFOLD APPROACH WITH INCLUSION OF STRETCH EFFECTS OF PURE HYDROGEN FLAMES

Hydrogen provides the most significant potential to meet the net-zero carbon target for the power generation and aviation propulsion, since it can be directly used in gas turbines. Its high energy density, higher auto-ignition temperatures, and ability to lean-burn are well suited for consumption in gas turbines. On the other hand, the high adiabatic flame temperature and reactivity need special attention for limiting the NOx emissions and the flashback risks. Therefore, the development of numerical models capable of predicting its behavior is essential to speed up the design phase of a new aero-engines combustor operating with pure hydrogen fuel. The present work aims to study through high-fidelity simulations a laboratory-scale rig investigated at the University of Berlin (TUB) featuring a swirl stabilized, premixed hydrogen flame. A tabulated chemistry approach based on the Flamelet Generated Manifold (FGM) is adopted for all the simulations, implementing key improvements to the canonic formulation. Specifically, a cost-efficient strategy to include the stretch and heat loss effects on flame reactivity is developed and tested to capture the peculiar behavior of hydrogen flames. Additionally, a hybrid approach based on FGM is proposed in which turbulence chemistry interaction is modeled through flame thickening. The model predictions are then analyzed in detail to highlight their differences, and a comparison with the available experimental data was performed to assess the most accurate model.