自由堆积多孔介质内预混燃烧火焰传播

Propagation of premixed combustion wave of methane/air in packed bed

为了解多孔介质内预混燃烧火焰前沿的传播特性,对不同化学当量比(=0.7～1.0)的甲烷/空气预混气体在不同孔隙率(ε为0.37和0.42)的多孔介质内的火焰前沿传播特性进行了研究,多孔介质采用3mm和6mm直径的Al2O3小球在陶瓷管中堆积而成。结果表明,预混气体在多孔介质中能够形成低速燃烧的稳定燃烧波;其火焰传播速度随化学当量比增大而加快,最大的火焰传播速度为3.52×10-3cm.s-1;多孔介质的结构对火焰前沿传播速度影响很大,即使在孔隙率差别不大的情况下,大球堆积而成的多孔介质比小球具有更高的火焰前沿传播速度。

Combustion wave propagation experiments in porous media were carried out for premixed methane/air mixtures with an equivalence ratio ranging from 0.7 to 1.0. Wave velocity, peak combustion temperature, and flame structure were studied. The parameters that affected these characteristics included inlet velocity, equivalence ratio, and structure of porous media. Experimental results showed that combustion wave propagation of a premixed mixture of methane/air combustion was possible at a very low velocity, and the wave velocity was determined by equivalence ratio and pore size of porous media. A larger equivalence ratio resulted in a larger combustion wave velocity. Porous media consisted of 6 mm diameter spheres had a larger combustion wave velocity than those consisted of 3 mm diameter spheres at the same porosity.