半密闭空间内煤尘云爆炸火焰传播过程及传播机制更为复杂，影响因素众多，爆炸过程中存在火焰、湍流与压力的相互耦合作用。为揭示开放管道内煤尘云形成机制及爆炸火焰行为动态演化特征，基于计算流体力学、燃烧学及数值传热学等理论，以开口的哈特曼管道为对象，分别对管道内煤尘扩散特征和爆炸过程进行模拟分析。基于物理实验验证及数值模拟研究，分析了煤尘在开口管道内的分散、悬浮及沉降特征，获取了粉尘扩散过程中流场的时空演化特征，得到了煤尘云爆炸过程中的温度变化规律，获取了爆炸过程中火焰动态行为及火焰高度、火焰速度的变化规律，研究了煤粉粒径及点火延时对火焰高度及火焰速度的影响规律，揭示了开放管道内煤粉云爆炸火焰传播的动力学机制。结果表明:①煤尘颗粒经过快速注入、减速分散、自由扩散和沉降阶段并最终形成粉尘云;② 在爆炸的不同阶段，影响火焰形态的因素不同;整个爆炸过程中，火焰阵面演化趋势为:“非球形—飞火及点状火—蘑菇状”;③ 随着爆炸的发展，火焰高度呈现Logistic函数特征，火焰速度呈现先迅速增大后缓慢减小；④ 湍流对均相燃烧及非均相燃烧的耦合影响造成了火焰锋面的不稳定性，火焰阵面热气流对管道口外侧冷气流的卷吸是形成“蘑菇状”火焰的主要原因。

The flame propagation process and propagation mechanism of coal dust cloud explosion in a semi-confined space are rather complicated due to numerous influencing factors.Moreover,there exists complex interaction between flame,turbulence and pressure during the explosion process.To reveal the dynamic evolution characteristics of flame behaviors and the formation mechanism of coal dust cloud in an open tube,the open Hartmann pipe was set as the simulation object,the diffusion characteristics and explosion process of coal dust in the open tube were simulated numerically based on the theory of computational fluid dynamics,combustion modeling,and numerical heat transfer.Furthermore,based on physical experimental validation and numerical simulation,the scattering,suspension,and sedimentation characteristics of coal dust in the open pipe were analyzed,the space-moments evolution characteristics of flow field dust diffusion process were obtained,the changing tendency for the temperature of coal dust clouds during the explosion process were acquired,the dynamic behaviors and the variation trend for flame height and flame velocity were revealed,the influence of coal particle size and ignition delay moments on the flame height and flame speed were investigated,finally,the dynamic mechanism for the flame propagation of coal dust cloud explosion in an open tube was put forward.Results showed that:① the formation of coal dust cloud goes through four different stages:fast injection,decelerating dispersion,free diffusion,and sedimentation.② The factors that affect the flame shape are different in various explosion stages; whereas,during the entire explosion process,the evolution trend of flame front plane is described as:“non-spherical-flying and point-shaped fire-mushroom”.③ With the development of the explosion,the flame height presents the Logistic function characteristics,while the flame velocity changes as the opening downward parabola.The coupling effect on homogeneous combustion and heterogeneous combustion from turbulence leads to the instability of flame front.

1 数值模型构建

   1.1 实验装置及物理模型

   1.2 模拟假设与受力分析

   1.3 数学模型与求解算法

2 结果与讨论

   2.1 开放管道内煤粉云形成过程及演化机制

   2.2 开放管道内煤粉云爆炸火焰动态行为及特征规律

   2.3 开放管道内煤粉云爆炸火焰传播动力学机制

3 结论