標題: Numerical analyses for radiative autoignition and transition to flame spread over a vertically oriented solid fuel in a gravitational field
作者: Lin, PH
Chen, CH
機械工程學系
Department of Mechanical Engineering
關鍵字: ignition;flame spread
公開日期: 2000
摘要: This study numerically investigates the ignition behaviors of vertically oriented cellulosic materials subjected to a radiant heat flux in a normal gravitational field. The entire process is delineated into two distinct stages. In the heating up stage, the maximum temperature increases with time but at a decreasing rate because of the pyrolysis reaction. The flame development stage consists of ignition and transition processes. In the ignition process, the maximum temperature in gas phase increases dramatically within a short period of time because a large amount of heat is generated from chemical reaction of the accumulative, flammable mixture. The flame is in a transition from a premixed flame to a diffusion one, except for the small region around the flame front. For the effect of varying the heating duration on ignition behavior, prolonging the imposed radiative heat time leads the ignition from a transition one to a persisting ignition. The effect of varying the solid fuel thickness indicates that the ignition delay time increases with an increase of solid fuel thickness while delta(S)less than or equal to 1.802. For 1.802 less than or equal to delta(S)less than or equal to 3.244, the ignition delay times remain constant. Finally, if the external heating rate is the same order as the heat diffuse rate, the ignition delay time increases with an increase in solid fuel thickness.
URI: http://hdl.handle.net/11536/30852
http://dx.doi.org/10.1080/00102200008924218
ISSN: 0010-2202
DOI: 10.1080/00102200008924218
期刊: COMBUSTION SCIENCE AND TECHNOLOGY
Volume: 151
起始頁: 157
結束頁: 187
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