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以聚氨酯泡沫为试样,建立了多孔介质水平燃料床阴燃的二维两相流数学模型.模型包括燃料吸热热解、燃料放热氧化及焦炭的放热氧化3个反应过程.通过有限单元法对聚氨脂泡沫的阴燃控制方程进行离散,并采用数值分析软件包FEMLAB进行计算求解.数值模拟了来流速度为0.28cm/s时燃料阴燃的温度分布和固体成分(燃料泡沫、炭粒和灰分)的变化,其中阴燃传播平均速度为0.0214cm/s,阴燃最高温度平均为644.67K;固体成分的变化曲线明显的将填充床分成4个区域:未燃区、燃料热解氧化区、焦炭氧化区及燃料燃尽区.同时,模拟研究了来流速度及燃料特性参数(导热率、比热、密度、孔隙直径等)对阴燃传播特性的影响.结果表明:阴燃速度和阴燃温度随着来流速度的增大基本上呈线性增长;燃料密度对阴燃传播影响最大;对于孔径较大的多孔介质燃料,模型中要考虑辐射的影响.模拟数据与实验数据进行了对比,结果基本吻合.
Taking polyurethane foam as sample, a two-dimensional two-phase mathematical model of smoldering combustion on porous media horizontal fuel bed was established.The model includes three processes of endothermic pyrolysis of fuel, exothermic oxidation of fuel and exothermic oxidation of coke, Element method was used to discretize the smoldering control equation of polyurethane foam and solved by numerical analysis software package FEMLAB.The temperature distribution and solid content of fuel smoldering were numerically simulated when the flow velocity was 0.28cm / , Charcoal and ash), the smoldering average velocity was 0.0214cm / s and the smoldering average temperature was 644.67K. The solid content curve clearly divided the packed bed into four zones: unburned zone, fuel Pyrolysis oxidation zone, coke oxidation zone and fuel burnout zone.At the same time, the effects of flow velocity and fuel parameters (such as thermal conductivity, specific heat, density and pore diameter) on smoldering propagation were simulated.The results showed that: The smoldering speed and smoldering temperature increase linearly with the increase of the flow rate. The density of fuel has the greatest influence on the smoldering transmission. For the porous medium with larger diameter, the influence of radiation should be considered in the model. Quasi data were compared with the experimental data, the results are consistent.