Numerical investigation of a coupled blow-off/flashback process in a high-pressure lean-burn combustor
Large eddy simulation is used to investigate the flashback mechanism caused by the combustion-induced vortex breakdown (CIVB) in a high-pressure lean-burn annular combustor with lean direct injection of kerosene. A single sector of the geometry, including a central pilot flame surrounded by a main flame, is simulated at take-off conditions. A previously-developed flamelet-based approach is used to model turbulence-combustion interactions due to its relatively low cost, allowing to simulate a sufficiently long time window. In stable operations, the flame stabilises in an M-shape configuration and a periodic movement of the pilot jet, with the corresponding formation of a small recirculation bubble, is observed. Flashback is then observed, with the flame accelerating upstream towards the injector as already described in other studies. This LES, however, reveals a precursor partial blow-out of the main flame induced by a cluster of vortices appearing in the outer recirculation region. The combined effect of vortices and sudden quenching alters the mixing level close to the injector, causing first the main, then the pilot flame, to accelerate upstream and initiate the CIVB cycle before the quenched region can re-ignite. Main and pilot flames partly extinguish as they cross their respective fuel injection point, and re-ignition follows due to the remnants of the reaction in the pilot stream. The process is investigated in detail, discussing the causes of CIVB-driven flashback in realistic lean-burn systems.
- Aeronautical, Automotive, Chemical and Materials Engineering
- Aeronautical and Automotive Engineering
Published inProceedings of the ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition
VolumeVolume 3B: Combustion, Fuels, and Emissions
SourceASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition
PublisherAmerican Society of Mechanical Engineers (ASME)
- AM (Accepted Manuscript)
Rights holder© ASME
Publisher statementThis paper was accepted for publication in the Proceedings of the ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition and the definitive published version is available in the ASME Digital Library at https://doi.org/10.1115/gt2022-82163.
Other identifierPaper No: GT2022-82163