Numerical analyses for radiative ignition and transition to flame spread over a horizontally oriented solid fuel in a gravitation field

P. H. Lin, W. F. Fan, Chiun-Hsun Chen*

*Corresponding author for this work

研究成果: Article同行評審

1 引文 斯高帕斯(Scopus)

摘要

This study numerically investigates the ignition behaviors of horizontal-oriented cellulosic materials subjected to radiant heat flux under a natural convective environment. This process can be divided into two stages: (1) the heating-up stage, during which the maximum temperature increases with time and (2) the flame development stage, consisting of the ignition and transition processes. The ignition process is marked with a sharp increase in maximum temperature. Meanwhile, the flame is in a transition from a premixed flame into a diffused one. In the transition process, the flame propagates upstream, forming a so-called opposed flame spread. There is a time lag between solid fuel pyrolysis and the gas-phase chemical reaction. The pyrolysis front overtakes the flame front in the initial heating-up process. As soon as the flammable mixture ahead of the flame front is ignited, the flame moves forward quickly, moving ahead of the pyrolysis front. The ignition delay time is shorter for a horizontal solid fuel than for a vertical solid fuel under the same environment, because the resultant high-temperature region is not cooled and the flammable mixture is not diluted by the induced flow in a horizontal solid fuel. For the effect of changing gravity, the ignition delay time decreases with a decrease in gravity level, owing to the smaller induced flow velocity.

原文English
頁(從 - 到)47-74
頁數28
期刊Combustion science and technology
173
發行號1
DOIs
出版狀態Published - 1 一月 2001

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