Frequency Analysis on the Flickering Behavior of Jet Diffusion Flame under Variable Gravity Fields.

Abstract

Effect of gravity level on the flickering motion was experimentally investigated for the propane and propane-hydrogen jet diffusion flames. A centrifuge was used for quantitative measurement of gravity effect, and frequency analysis was performed for the flickering flames. From the result of measurements under various gravity levels, it was clarified that the flickering frequency increased with an increase in the gravity level and it was correlated with two relationships expressed by the Strouhal number and the Froude number. One relationship was St∝Fr-0.41 for high Froude numbers (Frg100), and the other was St∝Fr-0.50 for low Froude numbers (Frl100). It meant that the Froude number gave the criterion of the flickering behavior and that flickering frequencies expressed by these two equations were affected by buoyancy in different ways. From the frequency analysis, it was found that oscillations of a flickering flame and a thermal convection around the flame were linked, but the characteristic of each flickering motion was different in the stability of periodicity.