气流特征对水平长管内石松子粉尘爆炸火焰结构的影响

为探索气流特征对水平长管内粉尘爆炸火焰结构的影响, 对采用加压送气传输方式形成的石松子粉尘云经静电引燃后其火焰在水平长管内的传播特性进行实验。利用热线风速仪测量不同气流条件下沿管径方向的速度分布和湍流强度分布, 采用高速摄像系统记录了火焰在水平管道内的传播过程。实验观察到, 即使管内石松子粉尘质量分数相同, 仍然会出现2种不同类型的火焰结构:一种类型火焰轮廓规则、清晰, 火焰中心为连续的黄色发光区并由红色边缘火焰包裹; 另一种类型火焰空间离散, 火焰发光区局部存在, 散乱地呈现不规则状态。详细分析不同气流条件对火焰结构的影响。

Effect of airflow characteristics on flame structure for following lycopodium dust-air mixtures in a long horizontal tube

Experiments were conducted to investigate the effect of conveying airflow characteristics on flame structure for the electric spark ignition in air flow of lycopodium dust.Hot wire anemometers were used to measure the distributions of velocity and turbulent intensity along the diameter in a 6 cm diameter and 4 m length horizontal acrylic tube of a blow-type pneumatic conveying system.The measured dust-air mixtures flowing velocities ranged between 10 and 30 m/s.A high-speed video camera was utilized to record the flame propagation process and to obtain the direct light emission photographs.Two apparently different types of flames appeared in the flame propagation process under different airflow conditions.Type A flame was characterized by a regular and continuous structure with the yellow light-emitting zone in the center surrounding by the red luminous zone.Type B flame was discrete in the space and the structure of the luminous zone was irregular.Furthermore, the flame propagation velocities, vortex structures, formation conditions and relative burning velocities of the two types flames under different airflow velocities were discussed in detail.