Combustion of Lean Flammable Mixtures in an Intense Radiation Field

Abstract

A combustion process showing a slow temperature rise was realized in an intense radiation field by burning a lean combustible mixture in a refractory-lined cylindrical combustion chamber in which a permeable board was placed at the upstream and downstream ends, respectively. It was found by the measurement of the temperature and composition of gas along with the ion current and by high-speed schlieren photography that a laminar flame was attached to the lower part of the red-hot refractory surface and that it spread toward the top center, even if the mixture strength was below the lean flammable limit. The flame becomes convex toward the unburnt mixture due to some instability resulting in a kind of cellular structure. The flickering of the flame, due partly to the wavy motion of the flame base and partly to the cellular structure, is the cause of the slow temperature rise.