多孔介质燃料填充床中反向阴燃传播解析

Analysis of reverse smoldering propagation in horizontally packed bed of porous medium

为了定性描述燃料反向阴燃中熄灭问题,根据单步反应机理,通过简化模型参数及大活化能渐近分析,得出了定性描述燃料反向阴燃传播的两个方程。结果表明:随着空气流量的增大,阴燃温度是不断上升的,但由于受到反向空气风流的影响,阴燃温度的增长幅度是逐渐变小的;阴燃传播速度却呈现出先增大后减小直至熄灭的变化趋势;在气体流量为零的情况下,燃料仍然可以发生阴燃,而维持阴燃不断传播所需要的氧气量源于反应区域周围气体的扩散。该项成果为科学理解燃料反向阴燃及其熄灭特性提供了理论依据。

In order to describe the quenching of the fuel reverse smoldering propagation,this paper presents two simplified equations to qualitatively depict the reverse smoldering propagation based on a one-step kinetic mechanism,the simplifications of model parameters and the asymptotic method.Case study shows that the smoldering temperature increases with the increase of airflow.However,the increasing amplitude is reduced due to the convective cooling of the preheat zone.With the increase of airflow,the smoldering propagation velocity increases to a maximum and decreases until quenching occurs at the maximum inlet airflow velocity.The qualitative analysis shows that the smoldering wave is also sustained by the oxygen present in the porous medium through the air diffusion although the supplied airflow is zero,namely,Mg=0.The study results provide a theoretical basis for understanding reverse smoldering propagation and its quenching.