$site = "publications.iafss.org"; $fullsite = "publications.iafss.org"; $basePath = "/home2/firesag5/private/data/"; ?>
Flame spread over thin layers of crude oil sludge has been studied. Flame spread experiments were performed by using a tray of 12 cm wide, 60 cm long and variable depth, installed in a temperature control bath. The aspects of spreading flames, the movements of leading and trailing flame edges, and the temperature distributions near leading flame edges were examined for various sludge layer thicknesses. The mode of flame spread was found to change at a moment several minutes after the start of flame spread. At the first stage, the flame spread rate was observed to be almost constant, while at the second stage, it changed periodically. The former was about twice as large as the latter. Two different limiting thicknesses were revealed. One was the limiting thickness for the initiation of flame spread and the other was that for the continuance of flame spread. Based on these results, the mechanisms of flame spread were discussed. All the flame spread phenomena were shown to be consistently interpretable by assuming similar mechanisms of flame spread as indicated in our previous study.