线性热流下可燃物着火时间的积分法预测

为了准确快速地预测可燃物的着火时间,根据积分方法的思想,推导了预测固体可燃物受线性变化热流作用的着火时间公式.采用PDE数值方法修正了该着火时间公式,并引入着火的表面温度判据,预测了泡桐,椿木,榆木和刺槐等4种木材在不同线性增长热流条件下的着火时间.这些着火时间和其他文献提供的实验数据进行了比较.结果表明:采用PDE修正后的积分模型在计算线性变化热流条件下,固体材料表面的温度变化,具有较高的精度.当热流增长率小于0.567 9 kW/(m~2·s)时,公式和实验得出的木材着火时间之间的误差一般在5%左右.

Predicting the Ignition Time of Combustibles Exposed to a Linear Heat Flux via an Integral Method

An integral formula was applied to predict the ignition time of solid combustibles. A linear heat flux was considered and the prediction is made quickly and precisely. The formula was modified by a PDE numerical method. The ignition times of paulownia, toon, elm and acacia woods heated at various rates were predicted in combination with the surface temperature. The calculated results were evaluated in reference to experimental data published elsewhere. The results show that the integral model, modified by the PDE method, calculates the surface temperature of solid materials heated by a linear heat flux accurately. The error between calculated and test ignition time data was within 5% when the heat flux increased at a rate less than 0.5679 kW/(m~2·s).