密闭空间煤粉气动分散湍流对爆炸参数的影响规律

采用自行设计的20 L长径比1∶1圆柱形透明有机玻璃罐、铸铁爆炸实验罐及对称式双喷头气动喷粉分散装置，研究了气动湍流强度、煤粉粒径及其爆炸特性，获得了不同实验条件下煤尘的爆炸特征参数,并给出了定量评价。实验结果表明在不同气动分散作用下，湍流均方根速度Urms测得1.1~6.2 m/s，平均湍流积分尺度在40~72 mm，雷诺数在8 000~16 300;爆炸超压峰值随湍流均方根速度呈线性增长，而爆炸超压上升速率Urms在1.1~3.5 m/s范围增速明显，Urms在3.5~6.2 m/s范围增速变缓。较大的湍流强度虽然具有加速煤粉与空气充分预混及自身反应，但同样导致对煤粉粒径间的传热传质效率下降;由最大有效燃烧速率理论计算与实验结果对比，也间接性的验证了实验结论的一致性。

Influence of turbulence flow on explosion characteristics of coal dust in 20 L vessel

The measurement of transient turbulent flow and coal dust explosion parameters were carried out in a 20 L cylindrical tank of transparent organic glass and an iron explosion experiment tank with two sets of pneumatic dispersed system,respectively.The turbulence characteristics and explosion parameters were studied under pneumatic pressures of 0.4-0.8 MPa.The results show that under different pneumatic pressures,the Urms is in the range of 1.1-6.2 m/s，the average turbulence integral scale is in the range of 40-72 mm,and Reynolds number is 8 000-16 300 in 100-250 ms.The explosion peak pressure is linear in the range of 1.1-6.2 m/s and increases from 0.78 MPa to 1.17 MPa.The increase of the dP/dt]max is obvious within a relative low velocity Urms of 1.1-3.5 m/s,and the increase of the dP/dt]max is slowing down in Urms of 3.5-6.2 m/s.Although larger turbulence intensity accelerates the blend and reaction of coal dust with air fully,it can also lead to a decrease in the efficiency of heat transfer and mass transfer between coal powder particles.By using the theory of ueff,max，the result is consistent with the dynamic change trend of the explosion intensity.