We study the evolution of premixed methane-air flames in large-scale obstructed channels using reactive CFD simulations. We vary the channel height d, the blockage ratio br, and the scaled distance between obstacles L/d to study their effects on the distance to DDT, L_DDT, and the distance to the shock-flame complex, L_SF. The results of simulations show two main effects. On one hand, the increase of br and decrease of L/d promote the flame acceleration and reduce L_SF and L_DDT. On the other hand, some configurations with higher br and smaller L/d prevent the detonation development. As a result, the leading shock and the flame never merge, and continue to propagate as a quasi-steady-state shock-flame complex. A collision of this complex with solid structures generates high pressures and strong reflected shocks that can ignite a detonation. This detonation would propagate in a shock-compressed material and result in extremely high pressures exceeding pressures of a regular detonation. Thus, the distance L_SF at which the shock-flame complex forms provides an important measure of a destructive potential in addition to L_DDT. This is particularly relevant for channels with high br where L_SF can be significantly shorter than L_DDT.

我们使用反应性CFD仿真研究了在大型阻塞通道中预混甲烷-空气火焰的演变。我们更改通道高度d，阻塞比br以及障碍物L / d之间的缩放距离，以研究它们对距DDT的距离L _DDT以及与冲击火焰复合体L _SF的距离的影响。仿真结果显示了两个主要影响。一方面，br的增加和L / d的降低会促进火焰加速并降低L _SF和L _DDT。另一方面，某些具有较高br和较小L / d的构型会阻止爆炸的发展。结果，领先的冲击和火焰永不融合，并继续以准稳态的冲击-火焰复合体的形式传播。这种复合物与固体结构的碰撞会产生高压和强烈的反射震动，从而可能引起爆炸。这种爆炸将在冲击压缩材料中传播，并导致极高的压力，超过常规爆炸的压力。因此，除了L _DDT之外，形成冲击火焰复合物的距离L _SF还提供了重要的破坏力度量。这对于具有高br的信道尤其重要，其中L _SF可能明显短于L _DDT。