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Numerical investigation of a coupled blow-off/flashback process in a high-pressure lean-burn combustor

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conference contribution
posted on 2023-02-20, 09:15 authored by Alessandro Soli, Ivan Langella

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.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Published in

Proceedings of the ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition

Volume

Volume 3B: Combustion, Fuels, and Emissions

Source

ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition

Publisher

American Society of Mechanical Engineers (ASME)

Version

  • AM (Accepted Manuscript)

Rights holder

© ASME

Publisher statement

This 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.

Publication date

2022-10-28

Copyright date

2022

ISBN

9780791886007

Other identifier

Paper No: GT2022-82163

Language

  • en

Location

Rotterdam, Netherlands

Event dates

13th June 2022 - 17th June 2022

Depositor

Alessandro Soli. Deposit date: 11 February 2023

Article number

V03BT04A010

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