雙壁轉鼓在不同轉速與壁面摩擦對於顆粒尺寸分離之研究

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题名:	雙壁轉鼓在不同轉速與壁面摩擦對於顆粒尺寸分離之研究
作者:	黃瑋智;Huang, Wei-Jhih
贡献者:	機械工程學系
关键词:	顆粒流;雙壁轉鼓;尺寸分離;過渡區;Granular flow;Double-walled drum;Size segregation;transition zone
日期:	2017-01-19
上传时间:	2017-05-05 17:42:16 (UTC+8)
出版者:	國立中央大學
摘要:	本研究主要探討雙壁轉鼓系統內填裝不同粒徑之顆粒時，在不同轉速之情形下產生之之顆粒尺寸分離現象。在實驗過程中，本研究利用DV 錄影機拍攝顆粒遷移變化與濃度變化之影像，再利用高速攝影機拍攝其運動過程，進而分析計算出在不同轉速與壁面摩擦效應下，粒子溫度隨著角度與徑向方向之變化。實驗結果顯示，當壁面為光滑的狀態時，在不同轉速之情況下，慣性力與重力為主導顆粒遷移之驅使力，從徑向方向之濃度變化中發現，當慣性力與重力效應同時影響分離過程時，將此時的顆粒特殊分布狀態稱為過渡區。本研究進一步於轉鼓壁面上黏貼砂紙，探討不同程度之壁面摩擦對於顆粒遷移的影響，當壁面黏貼砂紙時，除了受到驅使力的影響外，受到粗糙壁面的影響，壁面摩擦力隨之增加，大顆粒群將逐漸遠離作用壁面，造成過渡區發生的範圍變廣。當分離機制為慣性力所主導時，我們可由粒子溫度的分析中發現轉鼓中靠近內壁面之區域發生顆粒群的交互作用；隨著轉速的降低，顆粒發生交互作用之區域逐漸遷移至外壁面；以重力主導分離過程時，顆粒群之交互作用區域遷移至靠近外壁面處。若壁面黏貼砂紙時，壁面摩擦效應給顆粒更大的能量，整體粒子溫度皆高於壁面為壓克力材質之粒子溫度，且作用區域將更遠離作用壁面。;The purpose of this research is the size segregation in the double-walled drum in different rotational speeds and wall roughness conditions. A digital video recorder was used to photograph the variation of particle migrating and concentration, and a high speed camera was used to photograph the movement process of the particles. The granular temperature of experimental results was calculated based on the pictures from the high speed camera, and the results showed the variation trend along the radial directions and angles. The experimental results showed that the centrifugal force and gravity are the main drive forces influencing the size segregation. A special distribution state named Transition zone has been observed from the concentration changes along radial direction. Furthermore, a sandpaper was pasted on the walls of the drum, and therefore we analyzed the diversification of the particles segregation with angle and radial direction in different rough wall conditions. The interaction of coarse particles and fine particles were observed from the results of granular temperature. The interaction zone was closed to inner wall when the centrifugal force leading the segregation mechanism. On the contrary, the interaction zone was closed to outer wall when gravity leading the segregation mechanism. From the results of granular temperature, we have observed that the particles in the drum are given more energy with higher roughness wall, and vice versa. Hence, the transition zones of particles are moved away from the affecting wall.
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