空隙率变化及填充床表面下沉对阴燃传播的影响

Influences of Porosity and Surface Subsidence of Packed Bed on Smoldering Propagation

假定阴燃过程中 ,活性物、焦炭和灰三种物质的密度是恒定的 ,但它们各自占固体质量的份额随阴燃而改变 ,确定了阴燃过程固体颗粒的体积收缩速率及填充空隙率变化数学模型。对上方具有空气掠过的水平纤维质填充床 ,从点火到稳态传播的阴燃过程进行了模拟计算。计算结果表明 ,空隙率随阴燃过程增大 ,从而加快了阴燃传播速度 ,提高了其峰值温度。水平填充床表面下沉所引起的固

Based on the assumption that during smoldering process the densities of the active,char and ash remain constant,while their mass fractions in the solid substance vary with the smolering progression,a mathematical model forthe particle shrinkage rate and the packing porosity has been presented.Computational result show that the porosity increases with the smolder progression,consequently the smolder propagation rate and its peak temperature will be raised.On the other side,the influence of radiation heat exchange due to the packing surface subsidence can be neglected.