標題: Numerical analyses for radiative ignition and transition to flame spread over a horizontally oriented solid fuel in a gravitation field
作者: Lin, PH
Fan, WF
Chen, CH
機械工程學系
Department of Mechanical Engineering
關鍵字: radiative ignition;flame spread;solid fuel;gravitational field;horizontally oriented
公開日期: 2001
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.
URI: http://hdl.handle.net/11536/30032
http://dx.doi.org/10.1080/00102200108935844
ISSN: 0010-2202
DOI: 10.1080/00102200108935844
期刊: COMBUSTION SCIENCE AND TECHNOLOGY
Volume: 173
起始頁: 47
結束頁: 74
顯示於類別:期刊論文


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  1. 000175575000003.pdf