Fire Whirl due to Interaction between Line Fire and Cross Wind

Fire Safety Science Pub Date : 2014-01-01 DOI:10.3801/iafss.fss.11-1420

K. Zhou, Naian Liu, Panpan Yin, Xieshang Yuan, Juncheng Jiang, S. Key

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引用次数: 22

Abstract

During the wildland fire of Brazil in 2010 (http://www.dailymail.co.uk/sciencetech/article-1306088/Braziltornado-Whirling-column-flames-sweeps-burning-fields.html), a special fire whirl occurred over a narrow but long fire front and moved due to the wind effect. This paper presents an elementary study on such a moving fire whirl by conducting line fire experiments with cross wind. Experimental analysis indicates that a line fire near the ground, a reasonable attack angle between the line fire and the cross wind, and wind speed within a critical range are the three essential conditions for the formation of fire whirl in a line fire. By examining the advection and bending of vorticity, it is also deduced that the concentrated vortex of fire whirl results from the coupling of the line fire plume and the horizontal vortex line near the ground surface. By assuming the solid-body rotation of fire whirl flame, a possible mechanism of moving fire whirl is proposed, which states that the flame moving is mainly controlled by the drag force, lift force and ground friction. Accurate experimental measurements are needed to testify or verify this mechanism in the future work.

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线火与横风相互作用下的火涡

2010年巴西野火(http://www.dailymail.co.uk/sciencetech/article-1306088/Braziltornado-Whirling-column-flames-sweeps-burning-fields.html)时，在狭长的火线上出现了特殊的火旋风，并由于风的影响而移动。本文通过横风线火实验，对这种运动的火涡进行了初步研究。实验分析表明，近地面线火、线火与横风的合理攻角、风速在一定的临界范围内是线火形成火旋风的三个必要条件。通过对涡度平流和涡度弯曲的考察，还得出了火涡集中涡是线状火羽与近地面水平涡线耦合的结果。通过假设火焰旋转火焰的固体旋转，提出了火焰旋转运动的可能机理，即火焰的运动主要受阻力、升力和地面摩擦力的控制。在未来的工作中，需要精确的实验测量来证明或验证这一机制。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Fire Safety Science

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