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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0.5679 kW/(m2.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.
In order to predict the ignition time of combustibles accurately and quickly, the ignition time formula for predicting the linear heat flux of solid combustibles is deduced according to the idea of integral method.The PDE numerical method is used to correct the ignition time formula, and the ignition surface temperature According to the criteria, the ignition time of four kinds of wood, including paulownia, pimiento, elm and locust, were predicted under different linear growth heat flux.The ignition time was compared with the experimental data provided by other literatures.The results showed that after using PDE The integral model has high precision in calculating the temperature change of solid material surface under the condition of linearly varying heat flow.When the heat flow growth rate is less than 0.5679 kW / (m2.s), the difference between the formula and the experimentally obtained wood ignition time The error is generally around 5%.