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Flame propagation through large-scale vortical flows: effect of equivalence ratio. (English) Zbl 1337.35073

Summary: The present work is a continuation of previous studies of premixed gas flames spreading through a space-periodic array of large-scale vorticities, and is motivated by the experimentally known phenomenon of flame extinction by turbulence. The prior work dealt with the strongly non-stoichiometric limit where the reaction rate is controlled by a single (deficient) reactant. In the present study the discussion is extended over a physically more realistic formulation based on a bimolecular reaction involving two reactants with different molecular diffusivities, and where the mixture equivalence ratio is utilized as a control parameter. The flow-field is considered as prescribed and unaffected by combustion. The results obtained show that the dual influence of the large-scale turbulence on premixed combustion (flame speed enhancement followed by its reduction and extinction), and higher resilience of turbulent flames at lower Lewis numbers, are not actually related to the multiple-scale nature of the flow-field; the effects may well be captured within the framework of a one-scale flame-flow interaction scheme.

MSC:

35K57 Reaction-diffusion equations
80A32 Chemically reacting flows
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