Large eddy simulation and experimental study of flashback and blow-off in a lean partially premixed swirled burner

Lean premixed prevaporized (LPP) combustion is a widely used concept for reducing pollutant emissions in gas turbines. In LPP systems, a mixing tube is added between the injector and the combustion chamber to promote mixing and combustion efficiency. These devices are efficient to reduce pollutant emissions but can be sensitive to complex transient phenomena such as blow-off or flashback which are still beyond the prediction capabilities of most numerical tools. The present study describes a joint experimental and numerical study to evaluate the capacities of large eddy simulation (LES) for the prediction of flame dynamics in a swirl-stabilized LPP burner operated with propane. Combustion regimes are first identified experimentally: compact flames ( the normal regime for LPP and also flashback regimes where the flame is stabilized in the mixing tube) as well as lean blow-off situations are encountered. LES is then used to investigate each regime as well as the transition and the hysteresis phenomena between regimes. Flashback and blow-off limits are correctly reproduced and LES shows the crucial role of swirl and axial recirculation zones during flashback. More generally, this study demonstrates the potential of existing LES to study transient phenomena in flames.