期刊
COMBUSTION AND FLAME
卷 235, 期 -, 页码 -出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.combustflame.2021.111701
关键词
Swirl flame; Large-Eddy simulation; Precessing vortex core; Thermoacoustic instability
类别
资金
- Deutsche Forschungsgemeinschaft (DFG, GermanResearch Foundation) [GZ: SCHR 309/70-1, AOBJ: 639366]
The study investigates the impact of confinement on a turbulent lean premixed swirl flame using numerical simulation methods. The results show good agreement between numerical and experimental data in symmetric confined configuration, where confinement defines the recirculation zones and turbulence intensity of swirling jets.
The impact of confinement on a turbulent lean premixed swirl flame is investigated using a finitevolume large-eddy simulation method to solve the compressible Navier-Stokes equations and a combined G-equation progress variable approach to model the flame. The geometry is an experimentally investigated burner by Moeck et al. [Combust. Flame, 159, 2650-2668 (2012)] in which a precessing vortex core (PVC) and a self-excited thermoacoustic instability occur. To analyze the effect of confinement on the M-shaped flame, three configurations are investigated, i.e., an unconfined configuration, a symmetric confined configuration, and a non-symmetric confined configuration. The symmetric confined configuration corresponds to the experimental burner and the numerical results are in good agreement with the measurements. The flow fields of the confined and unconfined configurations differ significantly due to a more pronounced PVC downstream of the injection tube in the confined configurations. The numerical results confirm experimental findings from the literature, i.e., the confinement defines the recirculation zones and the turbulence intensity of the swirling jets. Furthermore, the present results show that the limit-cycle amplitude of the thermoacoustic instability, which occurs in the confined configurations due to a resonant coupling of the flame with the acoustic quarter-wave mode of the combustion chamber, is significantly reduced in the non-symmetric confined configuration. The mode determined by a dynamic mode analysis (DMD) that describes the impact of the acoustic quarter-wave mode on the velocity field only occurs in the symmetric confined configuration. Consequently, a lower coupling of the acoustic oscillations due to the thermoacoustic instability with the flame is evident. The results emphasize the sensitivity of the thermoacoustic instabilities on the confinement configuration and indicate the dependence of their oscillation amplitudes on the location of the swirl flame in the combustion chamber. (c) 2021 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
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