On the formation of spinning flames and combustion completeness for premixed fuel-air mixtures in stepped tube microcombustors

► Formation of high frequency spinning flames has been observed in stepped tube microcombustors. ► Formation of these spinning flames observed for methane-, propane-, and LPG-air mixtures. ► The frequency of these spinning flames is twice to that of earlier observed rotating flames. ► CO emissions are very low when combustor operates in spinning flame mode.