一种低湍流扬尘方法的实验研究

对一种新型扬尘方法在垂直管道中形成的扬尘湍流特性进行了测量,在此基础上,观察和测量了玉米粉尘火焰向上传播的过程,讨论了湍流对火焰特性的影响。新方法产生的扬尘湍流强度相当低,随时间衰减缓慢,扬尘湍流的积分尺度随着时间增大,约为2 cm到3 cm。实验中观察到两种粉尘火焰:湍流火焰和层流火焰,火焰形态转变对应的点火延迟时间约等于1．1 s,即粉尘云湍流运动强度为10 cm／s,湍流火焰传播速度明显大于层流火焰。

EXPERIMENTAL INVESTIGATION ON A LOW TURBULENCE DUST DISPERSION METHOD

An improved dust dispersion mechanism was designed, and the features of dispersion-induced turbulence were measured in a vertical duct. Based on this quantitative assessment, the upward flame propagation through cornstarch dust clouds was investigated with particular attention to the effect of turbulence on flame characteristics. The results show that the turbulence level induced by the dispersion process is much lower than those obtained with previous dispersion system. The decay of turbulence is slow. The integral scale of turbulence increases with time, and has a value of about 2 cm to 3 cm. With the increase of ignition delay time, two different kinds of dust flame were observed: turbulent and laminar flames. The transition occurs when the ignition delay time is about 1.1 s, corresponding to a turbulence level of 10 cm/s. The propagation velocity of turbulent flames is much higher than that of laminar flames.