Interactions of fires of neighbouring shrubs in two- and three-shrub arrangements
Interactions of fires of neighbouring shrubs in two- and three-shrub arrangements
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DOI：
10.1071/wf14089
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发表时间：
2015-08
影响因子：
3.1
通讯作者：
Ambarish Dahale;B. Shotorban;S. Mahalingam
中科院分区：
文献类型：
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作者：
Ambarish Dahale;B. Shotorban;S. Mahalingam
一个基于物理的计算模型被用来更好地理解由邻近灌木燃烧产生的火灾的相互作用。该模型包括流场湍流的大涡模拟和固体燃料和气相耦合的两相方法。考虑了两种不同的安排，包括两种和三种相同的灌木彼此相邻放置。所有的灌木都在各自的地面燃料的帮助下同时从基部点燃。冠状燃料和地面燃料均被建模为多孔介质，其热物理性质分别为紫砂和excelsior。模拟结果表明，随着灌木间距的增加，灌木内的峰值质量损失率和垂直火势蔓延率减小。在零间隔条件下，两灌木和三灌木布置的放热率分别提高了5%和15%。高重力转矩产生的强涡度可能是三灌木结构中燃烧增强的原因。这种效应在双灌木排列中要弱得多。两灌木和三灌木群落在中心距离分别为1.5倍和2倍灌木直径时停止相互作用。
A physics-based computational model was utilised to better understand the interactions of fires generated by burning of neighbouring shrubs. The model included large-eddy simulation for flow field turbulence and a two-phase approach for the coupling of solid fuel and gas phases. Two different arrangements consisting of two and three identical shrubs placed adjacent to each other were considered. All shrubs were simultaneously ignited from their base with the aid of separate ground fuels. Both crown and ground fuels were modelled as porous media with thermophysical properties of chamise and excelsior respectively. Modelling results indicated that the peak mass-loss rate and the vertical fire spread rate within a shrub decrease when the shrub separation distance increases. At zero separation, heat release rate normalised by the number of shrubs is enhanced by 5 and 15% for the two-shrub and the three-shrub arrangements, respectively. Generation of strong vorticity by higher gravitational torque appeared to be the cause for enhanced burning in the three-shrub arrangement. This effect was seen to be much weaker for the two-shrub arrangement. Interactions between the individual fires cease for a centre-to-centre distance of 1.5 and 2 times the shrub diameter for the two-shrub and the three-shrub arrangement respectively.