堆积尺寸对秸秆燃烧特性影响的实验研究

Experimental study on the influence of cumulated dimensions on the combustion characteristics of straw

秸秆是可能引起大规模山火的常见典型可燃物之一,自然堆积状态下秸秆的燃烧过程需要进行深入研究。开展了圆柱体秸秆的燃烧实验,直径分别为60 cm和90 cm,厚度从2.94 cm增加到12.23 cm。对比分析了不同工况下的秸秆燃烧过程,并对秸秆的质量损失速率、火焰温度等燃烧特性参数进行了分析。结果表明:秸秆燃烧过程可分为初始中心燃烧阶段、融合环火阶段、分离环火阶段和衰减熄灭阶段;秸秆的质量损失速率与厚度呈现明显的线性关系,且秸秆直径越大,质量损失速率也越大;火焰温度呈现“快速升高-缓慢降低”的趋势;火焰轴心温度随高度提高而逐渐降低,秸秆表面温度可达800℃,在0.9 m处的温度下降至200℃。研究结论有助于加深对秸秆火灾发展蔓延过程和特点的理解。

Straw is a typical common combustible that may cause wildfires. The combustion process of naturally cumulated is necessary to be studied. In this paper, the combustion experiments of cylindrical straw were carried out. The diameters were60 cm and 90 cm, and the thicknesses were from 2.94 cm to12.23 cm. The combustion process of straw under different conditions were compared, and the parameters of combustion characteristics such as the mass loss rate and flame temperature were analyzed. The results show that the straw combustion process can be divided into four stages, including initial central stage, merged annular stage, separated annular stage, and decay stage. The mass loss rate has an excellent linear relationship with the thickness of straw. And a larger diameter would cause a larger mass loss rate as well. The flame temperature presents a trend of“increase rapidly-decrease slowly”via time. The flame axis temperature decreases gradually with the elevated height,which is close to 800 ℃ near the straw surface and lower than200 ℃ at the height of 0.9 m. The conclusions benefit to deepen the understanding of the development and spread process and characteristics of straw fire.