初始线性火源的秸秆火焰蔓延及燃烧特性实验

Experimental on Fire Propagation and Combustion Characteristics of Rectangular Stacked Straw from a Line-source Fire

秸秆是引起山火的常见典型可燃物之一。为了有效预防由秸秆火灾引起的大规模山火,有必要对秸秆燃烧过程进行深入研究。开展了长度为1 m、宽度为0.1~0.6 m的初始线性火源的秸秆燃烧实验。对比分析了不同工况下的火焰蔓延扩散过程,并对秸秆的质量损失速率、火焰温度等燃烧特性进行了分析。结果表明:秸秆燃烧过程呈现匀速蔓延的特点,蔓延速率与秸秆宽度呈正相关关系;火焰前锋在宽度较窄时呈现凹形形状,在宽度较宽时呈现凸形形状。建立了秸秆的质量损失速率与火焰前锋横纵比的定量模型;火焰温度呈现快速升高-缓慢降低的趋势,秸秆表面温度超过500℃。研究结果有助于评估由秸秆燃烧造成的火灾危险程度。

The accidental fire of straw is a significant potential hazard.In order to prevent the large-scale wildfires caused by burning straw,it is necessary to study the development and features of fire propagation of straw.In this paper,the straw combustion experiments with an initial linear fire source with a diameter of 1 m and a width from 0.1 m to 0.6 m were carried out.The flame spreading and diffusion process under different conditions were compared and analyzed,and the combustion characteristics such as mass loss rate(MLR)and flame temperature,were analyzed.The results show that the straw combustion process shows the characteristics of uniform spread,and the spread rate is positively correlated with the straw width.The shape of flame front evolves from concave to convex as the width of the straw widens under the dominant mechanism of heat dissipation and air entrainment as well.The quantitative model between the mass loss rate of straw and the transverse to longitudinal ratio of flame front is established.The flame temperature shows a trend of“rapid increase-slow decrease”,and the surface temperature of straw exceeds 500℃.The conclusions are conducive to evaluating the hazard degree of wildfires.