孔隙流體對滾筒中顆粒流動之影響

Effect of interstitial fluid on a granular flowing layer in the drum

張軒源(Hsuan-Yuan Chang)

指導教授 ： 周憲德

國立中央大學/工學院/土木工程學系/碩士(2007年)

摘要

顆粒流廣泛的應用於各領域中，為了簡化濕顆粒所產生複雜之物理現象，一般僅考慮乾顆粒之流動情形。本研究為了探討孔隙液體對顆粒流動的影響，以滾筒作為實驗儀器，並加入不同濃度之甘油與水之混合液，並以粒子影像分析方法作為顆粒流研究之基礎。相關之運動特性大致與前人研究相符。本研究發現在滾動流況時，主、被動層之速度分佈可視為兩段線性分佈；於較低含液量時，流動層顆粒受表面張力及液體濃度的影響改變了顆粒在乾狀態時應有的流動特徵；高含液量時，滾筒邊壁因液體產生之潤滑效應，使顆粒產生新的擺盪型態，其特性與前人所述之擺盪有所不同；滾筒中顆粒隨福祿數與填充量不同而有不同之流動型態，實驗尺度比(D/d)的改變將影響相位圖的變化，而含水量之變化猶如降低尺度比，使相位圖流況區域產生變化。

關鍵字

顆粒流 ； 圓周福祿數 ； 滑脫速度 ； 液橋 ； 滾筒

並列摘要

Granular flow which was extensively applied in many field. A dominant aspect of granular flows is flow in thin surface layers while an understanding of the dynamics of dry granular surface flow has begun to emerge, the case of flow when air is replaced by a liquid is largely unexplored. This study discussed the granular flow effect of the interstitial fluid in the drum. Experiments were performed using particle tracking velocimetry(PTV) in a quasi-two-dimensional rotating tumbler to measure the velocity field within the flowing layer of monodisperse spherical particles, for a range of Froude numbers,fluid densities and fluid viscosities. The angle of repose with a liquid interstitial fluid are generally larger than for the dry system under similar conditions. At higher liquid content, lubrication forces play a role to general a new flowing regime in the drum; The dry granular in the drum have six flowing regimes with different Froude number and filling ratio. In this study compared the phase diagram with dry and wet system.

並列關鍵字

liquid bridge. ； slip velocity ； Froude number ； granular flow ； drum

參考文獻

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