To reveal the inner mechanism of gas explosion, the entire scenario of premixed flame front evolution within an accidental fire is prescribed. Specifically, "finger" flame shape, which is one of the key stages of flame evolution, is scrutinized with the situation of a methane-air explosion. A transition from a globally-spherical front to a finger-shaped one occurs when a flame starts approaching the passage walls. While this acceleration is extremely strong, it stops as soon as the flame touches the passage wall. This mechanism is Reynolds-independent; being equally relevant to micro-channels and giant tunnels. The flame speed increases by an order of magnitude during this stage. To implement dusty environments, Seshadri formulation for the planar flame [Combustion and Fiame 89 (1992) 333] is employed with a non-uniform distribution of inert dust gradients, specifically, linear, parabolic and hyperbolic spatial dust distribution gradients are incorporated into the "finger" flame shape. This study systematically investigates how the noncombustible dust distributions affect fire evolution, the flame shape, and propagation velocity.
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机译：为了揭示气体爆炸的内在机理，规定了意外火中预混火焰前沿演变的整个场景。具体来说，“手指”火焰形状是火焰发展的关键阶段之一，它是根据甲烷-空气爆炸的情况进行审查的。当火焰开始接近通道壁时，会发生从全局球形的前部到手指形的前部的过渡。尽管此加速度非常强，但一旦火焰接触到通道壁，它就会停止。该机制独立于雷诺。与微通道和巨型隧道同等重要。在此阶段，火焰速度增加了一个数量级。为实现多尘环境，采用平面火焰的Seshadri公式[Combustion and Fiame 89（1992）333]，采用惰性灰尘梯度的非均匀分布，特别是将线性，抛物线和双曲线空间灰尘分布梯度合并到“手指”的火焰形状。这项研究系统地研究了不可燃粉尘分布如何影响火势演变，火焰形状和传播速度。
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