Abstract
A number of studies about flame spread over solid combustibles have been reported over the past few decades. However, there are only a few studies about flame spread in a cylindrical enclosure. Especially, the static characteristics, such as flame height and width, have never been clarified. To reveal a geometrical similarity condition of flame spread in tube, we performed experiments in various conditions. The flame height increased as inner diameter, ambient pressure and oxidizer velocity increased. The non-dimensional flame height, determined as the flame height divided by the inner diameter, was proportional to Reynolds number. The flame spreading in different directions were compared and the shapes were almost similar to each other. It suggested that gravity effect on the flame shape was small. Meanwhile, the flame width did not depend on the flow field, and thus a quenching distance between the flame and the fuel surface was constant. From these results, it was found that the geometrical similarity condition was given by Reynolds number. In addition, considering the heat transfer from the flame to unburned fuel surface, we showed the similarity condition of the dynamic characteristic, i.e., non-dimensional flame spread rate. Also, the condition which can simultaneously satisfy both the static and the dynamic similarity was discussed in this paper.
