In the era when renewable energy resources are advocated, traditional fuels still account for a dominant proportion. During coal exploitation, coal dust explosion has been one of the most common and serious disasters. Nevertheless, the generated dust can suspend in the air, further leading to a secondary explosion. However, there are limited studies focusing on the propagation characteristics of secondary explosion induced by coal dust. Therefore, this paper aims to detect coal dust explosion in a pipe network and investigate the secondary explosion caused by the first explosion. In specific, this paper numerically analyzed the propagation characteristics of first and secondary explosion of coal dust in aspects of flame temperature, airflow rate and CO mass concentration. The results indicate that the maximum flame temperature of the secondary explosion of coal dust could reach up to 4500 K, which was more intense than the first explosion. After the secondary explosion, the air velocity witnessed a significant increase, compared with the first explosion, but the air velocity at the linear section of the pipe network witnessed the highest because of the air supplement at two sides. Different from the highest CO concentration at the ignition area in the first explosion, the CO concentration in the secondary explosion source area decreased rapidly and the maximum CO concentration appeared in the flame front. Moreover, because of enough oxygen supplement, the explosion reaction was much more sufficient, so that the maximum CO concentration was less than that in the first explosion.

中文翻译：

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煤尘二次爆炸传播特性研究

在倡导可再生能源的时代，传统燃料仍占主导地位。在煤炭开采过程中，煤尘爆炸是最常见，最严重的灾害之一。尽管如此，产生的粉尘仍会悬浮在空气中，进一步导致二次爆炸。但是，针对煤尘引起的二次爆炸的传播特性的研究很少。因此，本文旨在检测管网中的煤尘爆炸，并研究由第一次爆炸引起的二次爆炸。具体而言，本文从火焰温度，气流速率和CO质量浓度等方面对煤粉的一次和二次爆炸的传播特性进行了数值分析。结果表明，煤尘二次爆炸的最高火焰温度可以达到4500 K，比第一次爆炸还要高。在二次爆炸之后，与第一次爆炸相比，风速显着增加，但是由于两侧的空气补充，管网线性部分的风速最高。与第一次爆炸中点火区域的最高CO浓度不同，第二次爆炸源区域的CO浓度迅速下降，并且最大CO浓度出现在火焰前沿。而且，由于有足够的氧气补充，爆炸反应就足够了，因此最大的CO浓度小于第一次爆炸的浓度。