Transition to centrifuging granular flow in rotating tumblers: a modified Froude number
Transition to centrifuging granular flow in rotating tumblers: a modified Froude number
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过渡到旋转滚筒中的离心颗粒流：改进的弗劳德数
DOI：
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发表时间：
2011
影响因子：
3.3
通讯作者：
Richard M. Lueptow
中科院分区：
文献类型：
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作者：
G. Juarez;Pengfei Chen;Richard M. Lueptow
当颗粒向外抛射形成颗粒环时，颗粒物料在部分填充的旋转圆形滚筒机中发生离心，在滚筒机的外围形成固体旋转。实验研究了准二维转鼓离心临界转速与颗粒直径、转鼓填充率和间隙流体的关系。为了更好地理解摩擦对过渡的影响，采用离散元方法进行了定性数值研究。实验结果表明，干燥系统的临界转速不受颗粒直径的影响，除非填充分数大于75%，此时端壁摩擦开始发挥重要作用。临界速度与（1−φ）（−1/4）成正比，其中φ表示玻璃杯填充分数。静止角表示颗粒间的摩擦，也影响到向离心的过渡。最后，间隙流体，或者更确切地说，颗粒和间隙流体之间的密度差，影响测量的临界速度。提出了临界转速的修正项，以便更准确地表征旋转转杯中颗粒流向离心的过渡，从而得到修正的弗劳德数。
Centrifuging of granular material in a partially filled rotating circular tumbler occurs when particles are flung outward to form a ring of particles at the periphery of the tumbler rotating as a solid body. The critical rotation speed for centrifuging was studied experimentally in a quasi-two-dimensional tumbler as a function of particle diameter, tumbler fill fraction and interstitial fluid. A qualitative numerical study using the discrete element method was also conducted to obtain a better understanding of the impact of friction on the transition. Experimental results show that the critical rotational speed for dry systems is not affected by the particle diameter unless the fill fraction is above 75%, where endwall friction begins to play a significant role. The critical speed is proportional to (1−ϕ)(−1/4), where ϕ represents the tumbler fill fraction. The angle of repose, which represents inter-particle friction, also affects the transition to centrifuging. Finally, the interstitial fluid, or rather the density difference between the particles and the interstitial fluid, affects the measured critical speed. Correction terms for the critical rotational speed are proposed to more accurately characterize the transition to centrifuging for granular flow in rotating tumblers, resulting in a modified Froude number.