On the adequacy of certain experimental observables as measurements of flame burning rate

Journal Article · Fri May 01 04:00:00 EDT 1998 · Combustion and Flame

DOI:https://doi.org/10.1016/S0010-2180(97)00209-5· OSTI ID:619605

Najm, H N; Paul, P H; Mueller, C J; Wyckoff, P S ^[1]

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1. Sandia National Labs., Livermore, CA (United States)

This work presents detailed chemical kinetic computations and experimental measurements of a premixed stoichiometric N{sub 2}-diluted methane-air flame in two-dimensional unsteady vortical flow. The computed mole fraction of HCO is found to have excellent correlation with flame heat release rate over the whole range of unsteady curvature and strain-rate investigated, for the flame under consideration. HCO planar laser induced fluorescence (PLIF) imaging is discussed and demonstrated in a V-flame experiment. On the other hand, the authors find the utility of peak dilatation rate as an indicator of heat release rate to be dependent on the unsteady strain-rate and flame curvature environment, and the associated modification in diffusional thermal fluxes within the flame. The integrated dilatation rate is found to be more robust under unsteady strain-rate, but still questionable in regions of high flame curvature. They also study the utility of a particular formation for CO{sub 2}{sup *} chemiluminescence, OH, and CH PLIF imaging, as well as OH{sup *}, C{sub 2}{sup *}, and CH* chemiluminescence, as measurements of flame burning and heat release rates. Experimental results suggest that CH, OH{sup *}, C{sub 2}{sup *}, and CH{sup *} are not adequate indicators of local extinction; rather they provide signals of subtle shifts of hydrocarbon consumption among different chemical pathways. Moreover, numerical results suggest that both OH mole fraction and an existing CO{sub 2}{sup *} chemiluminescence model do not correlate with burning or heat release rate variations in regions of high unsteady flame curvature. The present numerical investigation uses a single flame/vortex condition and a specific 46-step C{sub (1)} chemical mechanism.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• OSTI ID: 619605
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 3 Vol. 113; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
COMBUSTION KINETICS
EXCITED STATES
FLAME PROPAGATION
FLAMES
MEASURING METHODS
METHANE
RADICALS
REACTION INTERMEDIATES