Flame Behavior and Height of Merging Fire Whirls from Multiple Fire Sources

Abstract

This paper presents a comprehensive experimental study on the mechanism of merging of fire whirls and the estimation of flame height. In the experiment, a tubular device made of 16 guide plates with adjustable angles was used. Tests were conducted using multiple fire sources arranged symmetrically on the circumference of the bottom of the device. When the guide plate angle was narrow, it was found that a fire whirl merges at a small separation distance. The complexity of the formation of the merged fire whirl was determined by the competition between the combustion enhancement due to the associated air and the enhancement of the inflow between the fire sources, which clearly differed from the characteristics of the merged flame in free space. Furthermore, on the basis of the result that the Froude model can be applied even to the merged fire whirl, a model formula for the flame height of the merged fire whirl was proposed. As a result, it was obtained that the useful information for determining the generation condition related to the fire whirl through the merging of multiple fire sources and the height of the flames.