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The Effect of Ground Roughness on Generation and Flow Patterns of Moving Fire Swirl

地面粗糙度对移动火旋流产生和流型的影响

基本信息

批准号：
12650504
负责人：
IKEDA Hirokazu
金额：
$ 2.5万
依托单位：
Utsunomiya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2003
项目状态：
已结题

项目摘要

Moving fire swirl is to be generated by interaction of the upward flow from fire region and general wind around the fire region. The purpose of this research is to clarify, in laboratory experiments, the effect of ground roughness on the flow patterns and flow field of the moving fire swirl. At first, experimental method was established to realize those phenomenon like moving fire swirl in the water flume experiment, that is, we injected steady upward flow into the flume flow from the bottom. The flow patterns were visualized with dye. The flow field was measured with electro-magnetic anemometer or image processing. The main result of this research is as follows.1)Moving fire swirl is generated only when the upward flow from the fire region is strong enough compared to the general wind. The flow patterns are divided into the fixed vortex type and shrunk vortex type by the Reynolds number with general wind velocity and fire region width. The effect of the ground roughness is to weaken the strength of the general wind.2)In the Fixed vortex type, strong currents toward upstream and upward are generated behind the fire region, which also generated intense turbulence.3) In the shrunk vortex type, each vortex moves down with decrease its votice and increase of an upward current.

移动火旋流是由火场内的上升气流与火场周围的一般风相互作用而产生的。本研究的目的是在室内实验中阐明地面粗糙度对运动火焰旋流流态和流场的影响。首先，建立了水槽实验中实现类似于移动火旋现象的实验方法，即从水槽底部向水槽内注入稳定向上的水流。用染料观察流动模式。流场测量采用电磁风速仪或图像处理技术。本文的主要研究结果如下：1）只有当来自火场的上升气流比一般的风强时，才会产生移动的火旋流。根据雷诺数与风速和火区宽度的关系，将流态分为固定涡型和收缩涡型。地面粗糙度的作用是减弱总风的强度; 2）在固定涡型中，火区后方产生了向上游和向上的强气流，并产生了强烈的湍流; 3）在收缩涡型中，各涡随着沃蒂采的减小和向上气流的增加而下移。