中文摘要：

对均匀空气流中微尺度甲烷扩散燃烧进行了数值模拟，重点考察微喷管内的流动和传热传质对微尺度燃烧特性的影响。研究结果表明，在保持燃料喷出速度一定的条件下，随着喷管直径的减小，喷管内与甲烷喷出速度相反方向上发生热量和质量的传递，燃料与空气的混合在喷管内已经发生，火焰的一部分热量回流到喷管内预热了未燃混合气，同时也增加了火焰的热损失。当管径为0．15mm时，甲烷在微喷管内就开始发生化学反应。在进行微尺度解析计算时，必须包含一定的喷管区域。

英文摘要：

The methane micro diffusion flames in micro nozzle in air are investigated numerically. We focus on the influence by heat and mass transfer in the nozzle on the characteristic of the flame. The results show that at constant low flow velocity conditions, with the inner diameter decreases, the transport of mass and heat happen in the opposite direction of methane flow velocity. The mixing process of fuel and air happens in the nozzle, and the mixture is preheated by the flame, the heat loss of the flame increases. When inner diameter is 0.15 mm, the combustion phenomenon takes place in the nozzle, releases heat. Therefore, it is necessary to consider and include the nozzle as the calculated zone when numerical computing the micro flames because of heat and mass transfer in the micro nozzle.