煤粉尘爆炸过程中火焰的传播特性

为了揭示煤粉尘爆炸过程中火焰传播特征，采用2种不同质量分数挥发分的煤粉在半封闭竖直燃烧管中进行实验。分别使用高速摄影装置和红外热成像装置记录火焰传播过程和空间的温度分布情况，并分析2种煤粉尘云的火焰传播速度和温度曲线。结果表明:在同等条件下，火焰在挥发分质量分数高的煤粉尘云中的传播速度和火焰温度要高于其在挥发分质量分数较低的煤粉尘云中的。煤粉尘云的体积质量和点火能量也影响着火焰的传播过程，随着煤粉尘云体积质量的增大，火焰的传播速度和火焰温度整体上呈现先增大后减小的趋势，在传播的后半段火焰速度出现震荡现象；随着点火能量的增大，火焰在煤粉尘云中的传播速度和最高温度也相应升高。通过大量的实验数据计算得到特定条件下火焰传播速度和温度的经验公式。

Characteristics of flame propagation during coal dust cloud explosion

Two kinds of different volatile pulverized coal were tested in a semi-enclosed vertical combustion tube.And a high-speed video camera and an infrared imager were used to record the flame propagation process and the spatial flame temperature distribution, respectively.The changes of the flame propagation velocity and temperature with time were analyzed for the two different coal dust clouds during combustion.Experimental results show that the flame propagation velocity and flame temperature of the high-volatile coal dust cloud are higher than those of the low-volatile coal dust cloud under the same experimental conditions.And the volumic mass of coal dust cloud as well as ignition energy can affect the flame propagation.With increasing the volumic mass of coal dust cloud, the flame propagation velocity and the flame temperature increase at first and then decrease, oscillating phenomena appear in the next process.With increasing the ignition energy, the flame propagation velocity and flame temperature increase.Based on the experimental data, an empirical formula was proposed for calculating the flame propagation velocity and flame temperature under certain conditions.