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@ARTICLE{Herff:894808,
      author       = {Herff, Sohel Sebastian and Pausch, Konrad and Loosen, Simon
                      and Schröder, Wolfgang},
      title        = {{I}mpact of non-symmetric confinement on the flame dynamics
                      of a lean-premixed swirl flame},
      journal      = {Combustion and flame},
      volume       = {235},
      issn         = {0010-2180},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier Science},
      reportid     = {FZJ-2021-03403},
      pages        = {111701},
      year         = {2022},
      abstract     = {The impact of confinement on a turbulent lean premixed
                      swirl flame is investigated using a finite-volume 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.},
      cin          = {JSC},
      ddc          = {620},
      cid          = {I:(DE-Juel1)JSC-20090406},
      pnm          = {5111 - Domain-Specific Simulation $\&$ Data Life Cycle Labs
                      (SDLs) and Research Groups (POF4-511)},
      pid          = {G:(DE-HGF)POF4-5111},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000735903800003},
      doi          = {10.1016/j.combustflame.2021.111701},
      url          = {https://juser.fz-juelich.de/record/894808},
}