垂直式振動床中漿態系統下不同黏度間隙流體對大顆粒與其動態行為的影響

The Brazil-nut effect in a quasi-2D vertical vibrated granular bed, in slurry system the larger particle with difference viscosity of interstitial liquid

林育賢(Yu-Hsien Lin)

指導教授 ： 蕭述三

國立中央大學/工學院/機械工程研究所碩士在職專班/碩士(2012年)

摘要

本文以實驗的方法探討在漿態系統下，類二維顆粒振動床內，不同黏度的間隙流體對於顆粒床中粒徑較大的大顆粒(或者稱為Intruder)的巴西豆現象之影響。本研究以高速攝影機擷取大顆粒在顆粒床裡的動態行為，並配合影像技術與粒子追蹤方法得到大顆粒隨著時間而上升之動態過程。
本研究發現在漿態系統下，間隙流體的黏度對於大顆粒上升的動態行為扮演重要的角色，當振動條件固定，間隙流體黏度越大時，大顆粒的上升時間與所受到的阻力都有隨間隙流體黏度增加而變大的趨勢，而上升速度與滲透長度則呈現相反趨勢。也發現無論在乾或濕系統下，大顆粒之上升時間隨著無因次振動加速度減少而增加，隨著振動頻率增加而增加。並且大顆粒之上升速度會隨著無因次振動加速度減少而減少，隨著振動頻率增加而減少。

關鍵字

間隙流體黏度 ； 粒子流 ； 巴西豆現象 ； 振動床 ； 漿態系統

並列摘要

This study investigates experimentally the Brazil-nut effect in a quasi-2D vertical vibrated granular bed, in slurry system the larger particle (or the so-called intruders) with difference viscosity of interstitial liquid. The Brazil nut effect means the larger particle rises to the top of the container and the smaller granular move to the bottom. The dynamics of the larger particle is recorded by using a high speed camera. By using image processing technology and the particle tracking method, the rise dynamic of the intruder was successfully measured and analyzed.
This study demonstrates that the interstitial fluid viscosity plays an important role in the rise dynamics of intruder in slurry system. The effects of vibration conditions and viscosity of interstitial liquid on the dynamics of intruder are investigated in the study. The results show that the rising time and drag force increases with increasing viscosity of interstitial liquid. But the rising velocity and penetration length decreases with increasing viscosity of interstitial liquid. It also shows that the rising time becomes slower as the smaller dimensionless vibration acceleration and the larger vibration frequency is applied in the granular system. Finally the rising velocity is enhanced with the increase of dimensionless vibration acceleration and is reduced with the increase of vibration frequency.

並列關鍵字

Granular flow ； Slurry System ； Vibrated Bed ； Braz

參考文獻

Liao, C. C., Hsiau, S. S., Tsai, T. H. and Tai, C. H., 2010, “Segregation to Mixing in Wet

Mobius, M. E., Cheng, X., Karczmar, G. S., Nagel, S. R. and Jaeger, H. M., 2004, “Intruders

Vertically Vibrated Beds of Granules,” Physical Review E, Vol. 54, pp. 874-883.

Bagnold, R.A., 1954, “Experiments on a Gravity-Free Dispersion of Large Solid Spheres in a

Effect: Competition Between Percolation and Condensation,” Physical Review Letters,