考虑弥散效应的多孔介质中超绝热燃烧的数值模拟

NUMERICAL STUDY OF SUPERADIABATIC COMBUSTION IN POROUS MEDIUM BY CONSIDERING THE DISPERSION EFFECT

研究多孔介质内往复流动下的超绝热燃烧。一维模型包括气体输运、多孔介质固体的辐射、导热和气固两相间的对流换热。通过数值计算研究超绝热燃烧的形成、以及弥散效应、当量比和多孔介质材料本身对超绝热燃烧特性的影响。计算结果的有效性通过实验进行了验证并取得了相同的趋势。结果表明,组分弥散效应对气体温度分布和反应热影响很小;同一工况下,不考虑气体混合物的热弥散效应,会导致过高的气体温度计算值。同时,计算结果表明小孔径的多孔介质更有利于贫可燃极限的扩展,对30 ppi的多孔介质燃烧器,得到了当量比为0．092的可燃极限。

Superadiabatic combustion with reciprocating flow in a porous medium has been investigated through numerical calculations. The one-dimensional model takes into account gas-phase transport, radiation, interphase heat exchange, and solid conduction. Attention was focused on the formation of superadiabatic combustion, the influence of gas dispersion effect, equivalence ratio and the porous media, on the major characteristics of superadiabatic combustion in the porous body. Resuits were validated through their comparison with available experimental data and show the same trends as the experimental results. The results show that species dispersion has little influence on the gas temperature and reaction heat for the lean mixture. However, the gas temperature is overpredicted at the reaction zone without the effect of mixture thermal dispersion at the same condition. In addition, it was shown that the combustible limit can be extended with smaller pore size porous media and a combustible limit with the equivalence ratio of 0.092 was achieved for 30 ppi Cerafoam