Modeling extinction and reignition in turbulent flames

Journal Article · Thu Dec 01 04:00:00 EST 2005 · Combustion and Flame

DOI:https://doi.org/10.1016/j.combustflame.2005.08.021· OSTI ID:20681458

Kronenburg, A; Kostka, M ^[1]

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1. Department of Mechanical Engineering, Imperial College London, Exhibition Road, London, SW7 2AZ (United Kingdom)

The conditional moment closure method (CMC) has been extended to improve reactive species predictions in flames with significant local extinction and reignition. Simple first-order closure of the conditionally averaged reaction rate term does not give satisfactory results due to large fluctuations around the conditional mean and an alternative closure is suggested here. The new closure is based on a precomputed parameterized reference field that maps reactive species mass fractions as functions of mixture fraction and sensible enthalpy. During the computations, the reference field is continuously adjusted to ensure consistency with the CMC solution and doubly conditioned chemical source terms that are functions of time, space, mixture fraction, and sensible enthalpy can thus be obtained. Integration over sensible enthalpy space yields the improved singly conditioned chemical source term that can be used for the solution of the CMC equations. Full closure can be achieved by assuming a {beta}-PDF for the probability distribution in sensible enthalpy space and an additional conditional variance equation needs to be solved. The overall agreement between the measured and the computed variance is satisfactory and the extended CMC model is applied to Sandia Flames D, E, and F. Excellent predictions of temperature, major species, intermediates, and NO are obtained in Flames D and E while temperature predictions can be significantly improved in Sandia Flame F.

• OSTI ID: 20681458
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 4 Vol. 143; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CALCULATION METHODS
ENTHALPY
FLAMES
FLUCTUATIONS
IGNITION
NITRIC OXIDE
REACTION INTERMEDIATES
TEMPERATURE DISTRIBUTION
TURBULENCE