甲烷/空气混合物在微小型钝体燃烧器中的燃烧特性

Combustion characteristics of methane/air mixture in micro-scale combustors with different bluff-bodies

为了实现在淬熄距离以下的稳定燃烧,试验设计了两种带钝体的回热型燃烧器,研究预混甲烷在高度小于淬熄距离的燃烧室中的燃烧特性。燃烧器的燃烧室高度为2 mm,长度为20 mm,进口处安装了边长为1mm的等边三角形钝体或相同尺寸的"V"形钝体,并在上下两侧设置了预热通道。利用Fluent6.3软件对甲烷/空气在这两个燃烧器的预混燃烧做了数值模拟,确定了浓度极限和速度极限,并对稳燃机理进行了分析。与三角形钝体燃烧器相比较,"V"形钝体燃烧器的稳燃范围更大。在所给出的稳定燃烧工况下两者的燃烧效率均在99%以上,甲烷/空气的混合气体能够完全燃烧。但当进气速度较小同时当量比较大时会发生回火现象。

Two kinds of combustors with a height less than the quenching distance were designed and the combustion characteristics were studied for stable combustion. The gap distance of the combustion chamber is 2 ram, and the length is 20 mm.An equilateral triangular bluff-body with a side length 1.0 mm or a ＂V＂ bluff-body of the same size is fitted near the entrance of the combus- tion chamber.There are two preheating channels on the upper and lower sides of the combustion chamber.Numerical simulation on methane/air premixed combustion in these combustors was per- formed and both velocity limits and concentration limits of the systems were decided.Compared with the combustor with a triangle bluff-body,the stable combustion ranges of the combustor with a ＂V＂ bluff-body were enlarged.The combustion efficiencies all stayed above 99%.But when the inlet mixture velocity was too small and equivalence ratios were relatively high, flashback would happen.