Simulations of a Swirl Stabilised Non-Premixed Hydrogen Flame With a Flamelet Generated Manifold Approach

Abstract This paper examines a swirl stabilised non-premixed dualswirl hydrogen burner using Large Eddy Simulation (LES) with a Flamelet Generated Manifold (FGM) combustion modelling approach, implemented into the commercial solver, STAR-CCM+. FGM is widely used in the gas turbine industry as it is less computationally expensive than detailed chemistry simulations due to pre-processing the chemistry. This paper aims to assess the ability for FGM-LES to predict isothermal and reacting conditions for two flame archetypes, lifted and attached, which result in both non-premixed and partially premixed flame fronts. Two grids are studied at isothermal and reacting conditions, with velocity field for both archetypes predicted well in both cases, however larger regions of RMS of velocity are seen for both grids, with the reacting simulations producing a higher magnitude. For the lifted condition, the flame remained attached to the injector lip. Two further studies are conducted, the first, modifying the boundary conditions at the hydrogen injector to account for a fixed temperature and progress variable of zero. This continued to result in a flame attached to the injector. The second, changed the reactor type within the FGM combustion model, also resulted in an attached flame. This suggests limitations to this FGM formulation in the prediction of the edge flame propagation speed. This test case has highlighted the need for further understanding of hydrogen combustion phenomena and how these are simulated using flamelet combustion methods.