Abstract
This paper treats the fluctuation of methane-air premixed flames formed on multiple small tubes. Premixed flames were formed on individual tubes when the equivalence ratio was around unity. We measured the fluctuation of brightness intensity of premixed flames and obtained the RMS and power spectrum density of the brightness fluctuation. The obtained RMS was considerably small because premixed flames were stable. The RMS slightly increased by increasing the equivalence ratio. The 1/f spectrum appeared in low frequency range, and the sharp peak in the power spectrum density was found at sufficiently large equivalence ratios. The present results suggest that the analysis of the brightness fluctuation is applicable to the diagnostics of premixed flames.
