Large Eddy Simulations of the ignition sequence of an annular multiple-injector combustor

The ignition transient is a critical fundamental phase in combustion systems that has strong practical implications. While this phenomenon has been extensively studied on single injector configurations, the burner-to-burner propagation of a full annular combustor is rarely investigated, due to the size and complexity of the geometry involved. To this purpose, an annular experimental setup has been developed at EM2C, featuring sixteen swirl injectors and quartz tubes providing a direct optical access to the flame. Ignition has been investigated systematically on this device, thus providing a large experimental database. In this work, this experiment is computed in the Large Eddy Simulation (LES) framework by carrying out massively parallel computations. This constitutes a unique comparison between experiments and calculations of a critical process for gas turbines. The ability of turbulent combustion models to properly retrieve the flame structure and propagation at the largest scales is not yet fully assessed and is investigated in this paper by comparing two conceptually different combustion modeling approaches, namely the filtered tabulated chemistry (F-TACLES) and the flame thickening with reduced chemistry (TFLES). Qualitative and quantitative comparisons between both simulations and experiment show an overall excellent agreement.