Experimental Study on Flame Wander of Fire Whirl

Abstract

In this paper, the flame wander of fire whirl is investigated by experimental means. Small-scale fire whirls were produced by two split cylinders, and the data of vertical velocity measured by stereo particle image velocimetry are analyzed to track the flame displacement along the horizontal direction. Medium-scale fire whirls were produced by a fixed wall facility, in which a video camera was used to monitor the flame position along the horizontal direction, thereby the flame displacements are determined by image analyses. It is found that during each test the flame displacements at different heights vary synchronously, suggesting that the flame is wandering as a whole. The flame displacements at different heights involve different variation ranges. By using the flame displacement data, the appearance probabilities of flame along the horizontal direction are calculated for small- and medium-scale fire whirls. The results show that the probabilities follow the Gaussian distribution, suggesting that a fire whirl almost always wanders at the very vicinity of the pool center. Finally, it is verified that the frequency of flame wander linearly depends on the circulation of fire whirl, while the correlation formulations differ between small-scale and medium-scale fire whirls.