液體黏度及含量對迴流強度影響之探討

本文主要在探討顆粒振動床內含有不同黏度及不同含量液體時對於顆粒床迴流運動所造成之影響。實驗方法是藉由改變液體黏度及含量來觀察一大顆粒體於小顆粒床內隨時間上升之過程，利用大粒子上升速度及邊壁粒子下降速度來表示顆粒振動床中迴流運動的強弱大小。本實驗發現在固定振動條件下，當不同黏度液體含量在少量的特定範圈內時，大粒子平均速度都有隨液體含量增加而上升的趨勢；但當液體含量高於某一臨界值之後，上升速度會隨著液體含量之增加而減弱。對於相同含量但黏度不同液體的比較，在添加較低黏度的液體時，大粒子上升平均速度較快，邊壁粒子下降速度變化也有類似上述狀況。本論文說明了液體黏度變化及液體含量的多寡對於顆粒振動床內迴流運動强弱的影響。

關鍵字

振動床；粒子流；迴流；分離；內聚力

並列摘要

The study investigates the effects of viscosity and content of liquid on convection strength in a vibrated granular bed. The one large glass bead was placed in a vibrated bed and the rising velocity of the one was measured to characterize the convection strength. The rising velocity of the large glass bead increased with increasing added content of liquid at small added content. As the added content of liquid was more than the critical value, the rising velocity of the large glass bead decreased with increasing added liquid content. The rising velocity was increased with decreasing viscosity of liquid. The dimensionless numbers were used to explain the effects of added liquid content and viscosity on convection strength of a vibrated granular bed in the paper.

並列關鍵字

Granular flow ； Vibrating bed ； Cohesion ； Segregation ； Convective flows

參考文獻

Brennen, C. E., Ghosh, S., and Wassgren, C. R, 1996, “ Vertical oscillation of a bed of granular material,” J. of Appl. Mech., Vol. 63,No. 1, pp.156-161.

Campbell, C. S. and Brennen, C. E., 1985, “Computer simulation of granular shear flows,” J. Fluid Mech., Vol. 151, pp. 167-188.

Chlenov, V. A. and Mikhailov, N.V., 1965, “Some properties of a vibrating fluidized bed,” J. of Eng. Phys., Vol. 9, pp. 137-139

Duran, J., Rajchenbach, J. and Clement, E., 1993, “Arching effect model for particle size segregation,” Phys. Rev. Lett., Vol. 70, pp. 2431-2434.

Evesque, P. and Rajchenbach, J., 1989, “Instability in a sand heap,” Phys. Rev. Lett., Vol. 69, No. 1, pp. 44-46.

國際替代計量

液體黏度及含量對迴流強度影響之探討

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