Porosity distribution is an important factor that affects premixed flame stability in packed beds. In this paper, the discrete element method is used to simulate the sphere packing in cylindrical, conical, and pyramidal packed beds. The anisotropic characteristics of porosity and ignition temperature distributions in packed beds are calculated and analyzed. The results show that the distance of the oscillation period of the packed bed filled with spheres of the same diameter is approximately equal to the sphere diameter. The oscillation amplitude of radial and axial porosity curves can be reduced by filling with mixed spheres of different diameters in cylindrical packed beds. The influence factors on the oscillation period distance of the radial and axial porosity curves include the diameter difference of the spheres and the mixing ratio of the number of spheres. In the cylindrical double-layer packed beds, the interfacial porosity can be decreased by the increase of the diameter difference among the spheres. Increasing the divergent angle of the conical packed beds can weaken the influence of wall effect on the radial and axial porosities, which makes the uniformity of the porosity in the conical packed beds better than that of the cylindrical and the pyramidal beds. The inhomogeneity of tangential porosity distribution in the packed beds is inherent. In the packed beds, the ignition temperature of premixed gas is negatively correlated with porosity, sphere diameter, equivalent ratio of mixed gas, and divergent angle of conical packed beds, and it is positively correlated with superficial velocity.

中文翻译：

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球体填充层孔隙率分布数值研究及点火不稳定性分析

孔隙率分布是影响填充床预混火焰稳定性的重要因素。在本文中，离散元法用于模拟圆柱、圆锥和锥体填充床中的球体填充。计算和分析了填充床孔隙率的各向异性特征和着火温度分布。结果表明，填充相同直径球体的填充床的振荡周期距离约等于球体直径。通过在圆柱形填充床中填充不同直径的混合球体，可以减小径向和轴向孔隙率曲线的振荡幅度。影响径向和轴向孔隙率曲线振荡周期距离的因素包括球体直径差和球体个数的混合比。在圆柱形双层填充床中，可以通过增加球体之间的直径差来降低界面孔隙率。增大锥形填充床的发散角可以减弱壁效应对径向和轴向孔隙率的影响，使锥形填充床的孔隙率均匀性优于圆柱形和锥形床。填充床中切向孔隙度分布的不均匀性是固有的。在填充床中，预混合气的着火温度与孔隙率、球径、混合气当量比、