Analysis of experimental flame shapes and blowout velocities of partially-premixed methane-air jet flames

Air/fuel partially-premixed flames may contribute to the suppression of the soot formation and thus, to reduction in the level of pollutant emissions. However, the combustion process may no longer be supported, depending the air/fuel ratio, hence leading to the blowout. This phenomenon can entail several industrial risks with severe consequences. This paper reports an experimental study of partially-premixed methane-air jet flames. Using broadband imaging, the flame-geometry descriptors and blowout occurrence are measured for different ranges of fuel flow rates and air-to-fuel volume ratios. Dimensionless correlations are developed for the geometrical features and the air/methane fuel ratios leading to blowout.