The effects of aspect ratio (α = 1, 2, 3 and 4) of mesoscale rectangular channels on CH₄-air flame stability were numerically studied. The results show that at relatively high inlet velocity, the flame is convex (with respect to the upstream) when α ≤ 3; instead it shifts to a W-shaped appearance at α = 4. In addition, the flame blowout limit exhibits a non-monotonic variation and it peaks at α = 3. Our analysis reveals that when α is raised from 1 to 3, both of the heat loss ratio and hydrodynamic perturbation rate are reduced, which favors a larger blowout limit. However, for the channel with α = 4, the perturbation rate of hydrodynamic instability is significantly increased at the flame tip because of the increased wave number, which results from the W-shaped flame front. Consequently, the intensified hydrodynamic instability will lead to a reduction in the flame blowout limit of the channel with α = 4.

中尺度矩形通道的纵横比（α= 1、2、3和4）对CH _4的影响对空气火焰稳定性进行了数值研究。结果表明，在较高的入口速度下，当α≤3时，火焰是凸形的（相对于上游）。取而代之的是，它在α= 4时转变为W形外观。此外，火焰喷出极限呈现出非单调变化，并且在α= 3时达到峰值。我们的分析表明，当α从1增加到3时，两个热损失率和流体动力扰动率降低，这有利于更大的井喷极限。但是，对于α= 4的通道，由于W形火焰前沿导致的波数增加，因此火焰动力扰动率在火焰尖端显着增加。因此，加剧的水动力不稳定性将导致α= 4的通道的火焰喷出极限降低。