Abstract Experiments were carried out in the Idealized-Firebrand Ignition Test (I-FIT), a bench scale apparatus specifically designed to test the ignition of forest fuel layers from a representative firebrand. A cylindrical heater was used to model the firebrand, which allowed to control the incident radiative heat flux on the specimen, from the critical heat flux up to 25 kW/m2, for five different porosities of the fuel layer. Experimental ignition delay times were interpreted based on a theoretical model of the radiative heating of the fuel layer. Radiative heat transfer within the fuel layer was modeled by using the P 1 approximation. In the limit of small ignition delay times an analytical expression was derived to correlate the inverse of the ignition time to the incident heat flux. This analytical expression is used to obtain the ignition temperature and effective properties for the forest fuel layers, namely the product of the fuel volume fraction by solid fuel density and solid heat capacity. Analytical solutions were found to be consistent with experimental data and a correlation relating the inverse of the non-dimensional time-to-ignition to the non-dimensional heat flux is provided.

中文翻译：

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通过理想化的火把点燃荒地燃料

摘要 实验是在理想化火点点火测试 (I-FIT) 中进行的，这是一种专门设计用于测试来自代表性火点的森林燃料层点火的台式设备。圆柱形加热器用于模拟火种，它允许控制试样上的入射辐射热通量，从临界热通量到 25 kW/m2，燃料层的五种不同孔隙率。基于燃料层辐射加热的理论模型解释了实验点火延迟时间。燃料层内的辐射传热是通过使用 P 1 近似来模拟的。在小点火延迟时间的限制下，导出了一个解析表达式，以将点火时间的倒数与入射热通量相关联。该解析表达式用于获得森林燃料层的点火温度和有效特性，即燃料体积分数与固体燃料密度和固体热容的乘积。发现解析解与实验数据一致，并且提供了将无量纲点火时间的倒数与无量纲热通量相关联的相关性。