Blended combustion has a potential to promote flame stability under micro-scale condition. For this, the effect of dimethyl ether (DME) addition on the flame stability of premixed methane/air confined within a quartz combustor is explored through experimental approach. Seven flame propagation modes are observed for pure methane-air combustion. Experimental results indicate that flame stability could be remarkably enhanced, especially under fuel-lean conditions, and the flame is able to sustain stable combustion for some extreme circumstances with DME addition. To further understand the underlying mechanism of enhanced flame stability, detailed analyses regarding flame shape range and flame transition point as a function of blended ratio are also conducted. The existence range of various flame shapes can be generally broadened to some degree as increasing blended ratio, which is due to the increased value of flame transition point. Furthermore, it is found that variation frequency of weak flame decreases with an increase in blended ratio and inlet velocity. For sufficiently high blended ratio under fuel-lean condition, oscillating flame disappears, which indicates that flame is much more stable in this case. The reason for enhanced flame stability could be related to the increased flame speed and large extinction strain rate with DME addition.

混合燃烧在微尺度条件下具有促进火焰稳定性的潜力。为此，通过实验方法研究了添加二甲醚（DME）对封闭在石英燃烧器中的甲烷/空气预混合气体火焰稳定性的影响。对于纯甲烷-空气燃烧，观察到七个火焰传播模式。实验结果表明，火焰稳定性可以得到显着提高，尤其是在燃料稀少的情况下，并且在添加DME的某些极端情况下，火焰能够维持稳定的燃烧。为了进一步理解增强火焰稳定性的潜在机理，还进行了有关火焰形状范围和火焰转变点随混合比变化的详细分析。随着混合比的增加，各种火焰形状的存在范围通常可以扩大到一定程度，这是由于火焰转变点的值增加所致。此外，发现随着混合比和入口速度的增加，弱火焰的变化频率减小。对于在稀燃条件下足够高的混合比，振荡火焰消失了，这表明在这种情况下火焰要稳定得多。添加DME可以提高火焰速度，并提高消光应变率，从而提高火焰稳定性。对于在稀燃条件下足够高的混合比，振荡火焰消失了，这表明在这种情况下火焰要稳定得多。添加DME可以提高火焰速度，并提高消光应变率，从而提高火焰稳定性。对于在稀燃条件下足够高的混合比，振荡火焰消失了，这表明在这种情况下火焰要稳定得多。添加DME可以提高火焰速度，并提高消光应变率，从而提高火焰稳定性。