木材阴燃传播的自熄与自维持模拟研究

A Computational Study on the Self-Extinguished and Self-Sustained Smoldering of Wood

木材阴燃传播会演变成自熄或自维持的火灾形式.基于多组分平行热解氧化的五步反应模型,验证了阴燃前锋深度作为木材阴燃演变临界条件的可行性,并研究了阴燃特征温度、热流和厚度对木材阴燃演变临界条件的影响.模型较好地复现了不同阴燃前锋深度下的木材阴燃自熄和自维持传播.研究发现,临界阴燃前锋深度随着阴燃特征温度和热流的增大而减小,5~10 mm是阴燃传播的特征厚度,在阴燃传播到达到此深度后,自维持的传播更容易发生,且受热流的影响较小.一旦达到临界条件,无论厚度的大小,阴燃始终能够维持传播.

The smoldering propagation of wood will evolve into a self-extinguished or self-sustained state.Based on a five-step reaction model,this work verifies the feasibility of the smoldering front depth as the threshold of smoldering evolution of wood.The effect of smoldering characteristic temperature,heat flux and thickness were studied.The model precisely reproduced the self-extinguished and self-sustained smoldering of wood for various smoldering front depths.The modelled critical smoldering front depth decreases with the increase of smoldering characteristic temperature and heat flux.5—10 mm is the characteristic thickness of smoldering propagation,and when the smoldering propagates to this depth,the self-sustained propagation will easily occur and hardly be af-fected by external irradiation.Once the critical depth is reached,the smoldering will remain self-sustained regard-less of thickness.