Experimental Analysis on Flame Flickering of a Swirl Partially Premixed Combustion

Abstract

An experiment was conducted to explore the flickering parameters under varying mass flow rate of fuel m ˙ F with spatial analysis and global analysis. The parameters include mean value, flickering weighted average frequency F, flickering coefficient of variation cv (firstly introduced), skewness s, and kurtosis k. From the spatial analysis, it was found that the brightest part of flame is located in its core, and the brightness gradually decreased from the inside out. The distributions of high levels of F, cv, s, and k are almost consistent, all lying in the flickering edge, which is a thin layer where the parameters sharply declined. From the global analysis, with the increment of m ˙ F, the global F decreased slightly; the global cv declined uniformly, which means the oscillation amplitude diminished and thus the flame became more stable; the global s linearly reduced; and the global k also showed a decreasing trend. The decreasing global s indicates that the number distribution gradually became symmetric, and the decreasing global k indicates that the number distribution progressively became flat. Consequently, the number distribution progressively tends to normal distribution at larger m ˙ F.