Effects of porosity and area density on upward flame spread characteristics over thin flax fabric
Effects of porosity and area density on upward flame spread characteristics over thin flax fabric
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DOI：
10.1177/0040517520947746
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发表时间：
2020-08
影响因子：
2.3
通讯作者：
Yunji Gao;Hui Zhu;Yu-chun Zhang;Guoqing Zhu;Guoqiang Chai
中科院分区：
文献类型：
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作者：
Yunji Gao;Hui Zhu;Yu-chun Zhang;Guoqing Zhu;Guoqiang Chai
尽管多孔性是织物燃料的一个特殊性质，但很少有研究系统地研究织物燃料向上火焰传播的多孔性效应。本文研究了不同孔隙率和面密度的亚麻织物样品的孔隙率和面密度对火焰向上传播的影响。得到并分析了火焰形状、火焰长度、火焰传播速率、点火时间、靶距和表面温度分布。主要研究结果如下：随着孔隙率的增加和相应的面密度的降低，火焰传播速率和火焰长度增加，而着火时间缩短，这是因为氧气更容易到达热解区的燃料表面，从而使原始燃料接收的热通量增加。预热区火焰喷距和表面温度这两个参数可以用来表征原始燃料接收到的热流。当孔隙率增大，面密度减小时，火焰离体距离和距热解前沿相同距离处的表面温度均增大，表明原始表面接收到的热通量增大。
Few investigations have systematically addressed the porosity effects of upward flame spread over fabric fuels, although the porosity is a special property for fabric fuels. The present paper studies the porosity and area density effects on upward flame spreading using 160.0 cm tall and 8.0 cm wide flax fabric samples with various porosities and area densities. The flame shape, flame length, flame spread rate, ignition time, standoff distance and surface temperature distribution are obtained and analyzed. The major findings are summarized as follows: as the porosity increases and corresponding area density declines, the flame spread rate and flame length increase, whereas the ignition time decreases, which is because the oxygen can reach the fuel surface in the pyrolysis region more easily and, subsequently, the heat flux received by the virgin fuels increases. The two parameters of flame standoff distance and surface temperature in the preheating region can be applied to characterize the heat flux received by the virgin fuels. Generally, when the porosity increases and the corresponding area density decreases, the flame standoff distance and the surface temperature at the same distance from pyrolysis front increase, which reveals that the heat flux received by the virgin surface increases.