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Turbulent flame-wall interaction: a direct numerical simulation study

Turbulent flame-wall interaction: a direct numerical simulation study

Kategori
Tidsskriftspublikasjon
Sammendrag
A turbulent flame–wall interaction (FWI) configuration is studied using three-dimensional direct numerical simulation (DNS) and detailed chemical kinetics. The simulations are used to investigate the effects of the wall turbulent boundary layer (i) on the structure of a hydrogen–air premixed flame, (ii) on its near-wall propagation characteristics and (iii) on the spatial and temporal patterns of the convective wall heat flux. Results show that the local flame thickness and propagation speed vary between the core flow and the boundary layer, resulting in a regime change from flamelet near the channel centreline to a thickened flame at the wall. This finding has strong implications for the modelling of turbulent combustion using Reynolds-averaged Navier–Stokes or large-eddy simulation techniques. Moreover, the DNS results suggest that the near-wall coherent turbulent structures play an important role on the convective wall heat transfer by pushing the hot reactive zone towards the cold solid surface. At the wall, exothermic radical recombination reactions become important, and are responsible for approximately 70% of the overall heat release rate at the wall. Spectral analysis of the convective wall heat flux provides an unambiguous picture of its spatial and temporal patterns, previously unobserved, that is directly related to the spatial and temporal characteristic scalings of the coherent near-wall turbulent structures.
Oppdragsgiver
  • Norges forskningsråd / 193816
Språk
Engelsk
Forfatter(e)
  • Gruber Andrea
  • Sankaran Ramanan
  • Hawkes Evatt R
  • Chen Jacqueline H
Institusjon(er)
  • SINTEF Energi AS / Termisk energi
  • Oak Ridge National Laboratory
  • University of New South Wales
  • Sandia National Laboratories
År
2010
Publisert i
Journal of Fluid Mechanics
ISSN
0022-1120
Forlag
Cambridge University Press
Årgang
658
Side(r)
5 - 32