Stationary combustion regimes, their linear stability and extinction limits of stretched premixed flames in a narrow gap between two heat conducting plates are studied by means of numerical simulations in the framework of one-dimensional thermal-diffusion model with overall one-step reaction. Various stationary combustion modes including normal flame (NF), near-stagnation plane flame (NSF), weak flame (WF) and distant flame (DF) are detected and found to be analogous to the same-named regimes of conventional counterflow flames. For the flames stabilized in the vicinity of stagnation plane at moderate and large stretch rates (which are NF, NSF and WF) the effect of channel walls is basically reduced to additional heat loss. For distant flame characterized by large flame separation distance and small stretch rates intensive interphase heat transfer and heat recirculation are typical. It is shown that in mixture content / stretch rate plane the extinction limit curve has ε-shape, while for conventional counterflow flames it is known to be C-shaped. This result is quite in line with recent experimental findings and is explained by extension of extinction limits at small stretch rates at the expense of heat recirculation. Analysis of the numerical results makes possible to reveal prime mechanisms of flame quenching on different branches of ε-shaped extinction limit curve. Namely, two upper limits are caused by stretch and heat loss. These limits are direct analogs of the upper and lower limits on conventional C-shaped curve. Two other limits are related with weakening of heat recirculation and heat dissipation to the burner. Thus, the present study provides a satisfactory explanation for the recent experimental observations of stretched flames in narrow channel.

在一维热扩散模型与整体一步反应的框架内，通过数值模拟的方法研究了稳态燃烧状态，其线性稳定性和在两个导热板之间的狭窄间隙中拉伸的预混火焰的熄灭极限。检测到各种固定燃烧模式，包括正常火焰（NF），近停滞平面火焰（NSF），弱火焰（WF）和远距离火焰（DF），发现它们类似于常规逆流火焰的同名体制。对于以中等和较大的拉伸速率（即NF，NSF和WF）稳定在停滞平面附近的火焰，通道壁的影响基本上减少了，导致了额外的热损失。对于以大的火焰分离距离和小的拉伸速率为特征的远处的火焰，典型的是密集的相间传热和热再循环。结果表明，在混合物含量/拉伸速率平面内，消光极限曲线为ε形，而对于常规的逆流火焰，已知为C形。该结果与最近的实验结果非常吻合，并且可以通过以较小的拉伸速率扩展消光极限来进行解释，而这是以热循环为代价的。对数值结果的分析使得揭示ε形消光极限曲线不同分支上的火焰淬火的主要机理成为可能。即，两个上限是由拉伸和热损失引起的。这些限制是常规C形曲线的上限和下限的直接类似物。另外两个限制与热循环的减弱和燃烧器的散热有关。因此，本研究为狭窄通道中拉伸火焰的最新实验观察提供了令人满意的解释。