Experimental investigation of stabilization mechanisms in turbulent, lifted jet diffusion flames

Journal Article · Wed Feb 01 04:00:00 EST 2006 · Combustion and Flame

DOI:https://doi.org/10.1016/j.combustflame.2005.08.010· OSTI ID:20700732

Su, L K; Sun, O S ^[1]; Mungal, M G ^[2]

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1. Applied Fluid Imaging Laboratory, Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States)
2. Thermosciences Division, Mechanical Engineering Department, Stanford University, Stanford, CA 94305 (United States)

Simultaneous planar-laser induced fluorescence (PLIF) and particle image velocimetry (PIV) provide a comprehensive view of the molecular mixing and velocity fields in the stabilization region of turbulent, lifted jet diffusion flames. The Mie scattering medium for PIV is a glycerol-water fog, which evaporates at elevated temperatures and allows inference of the location of the high-temperature interface at the flame base. The jet Reynolds numbers vary from 4400 to 10,700. The mixing and velocity fields upstream of the flame base evolve consistently with nonreacting jet scaling. Conditional statistics of the fuel mole fraction at the instantaneous high-temperature interface show that the flame stabilization point does not generally correspond to the most upstream point on the interface (called here the leading point), because the mixture there is typically too lean to support combustion. Instead, the flame stabilization point lies toward the jet centerline relative to the leading point. Conditional axial velocity statistics indicate that the mean axial velocity at the flame front is {approx}1.8S{sub L}, where S{sub L} is the stoichiometric laminar flame speed. The data also permit determination of the scalar dissipation rates, {chi}, with the results indicating that {chi} values near the high-temperature interfaces do not typically exceed the quenching value. Thus, the flame stabilization process is more consistent with theories based on partial fuel-air premixing than with those dependent on diffusion flame quenching. We propose a description of flame stabilization that depends on the large-scale organization of the mixing field. (author)

• OSTI ID: 20700732
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 3 Vol. 144; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
COMBUSTION KINETICS
FLAMES
JETS
STABILIZATION
TURBULENCE
VELOCITY