Premixed flat flame methane

Fig. 16.8 Illustration of a premixed flat-flame burner. Fuel and oxidizer are first premixed, and then flow through a porous burner face. A steady, one-dimensional flat flame is stabilized by heat transfer to the cooled burner face. The solutions shown here are for a methane-air flame, in which the air contains water vapor at 100% relative humidity. By plotting the temperature and selected species profiles, one can observe some of the complexities of flame structure.

The experimental setup for diode-laser sensing of combustion gases using extractive sampling techniques is shown in Fig. 24.8. The measurements were performed in the post-flame region of laminar methane-air flames at atmospheric conditions. A premixed, water-cooled, ducted flat-flame burner with a 6-centimeter diameter served as the combustion test-bed. Methane and air flows were metered with calibrated rotameters, premixed, and injected into the burner. The stoichiometry was varied between equivalence ratios of = 0.67 to... 

Fig. 13.11 Low-pressure, premixed, methane-air, flat flame with a molecular-beam mass-spectrometry probe positioned above the flame [187]. Photograph is courtesy of Dr. A. Mcllroy, Sandia National Laboratiories.

Two flat flame burners have been employed, a 4 cm 10 cm burner with a ceramic-lined chimney for NO measurements (4) and a 2.6 cm x 8.6 cm open-faced burner with a nitrogen shroud flow for CO measurements. Both burners operate at atmospheric pressure with laminar, premixed methane-air mixtures. These burners work satisfactorily over a broad range of fuel-air equivalence ratios, but both have cold boundary regions which cause non-uniform conditions along the optical axis that can be important in the data analysis (4). 

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