非球形顆粒體在剪力槽中的流動行為追蹤與分析

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题名:	非球形顆粒體在剪力槽中的流動行為追蹤與分析
作者:	謝仲庭;Hsieh, Jhong-Ting
贡献者:	機械工程學系
关键词:	非球形顆粒體;剪力槽實驗;卡式粒子追蹤法;改良式粒子追蹤法;傳輸性質;Non-spherical particle;Couette flow device;The Voronoï imaging methods;Improved Particle Tracking Velocimetry;Transport property
日期:	2018-11-02
上传时间:	2019-04-02 15:10:48 (UTC+8)
出版者:	國立中央大學
摘要:	本研究旨在探討非球形顆粒體在剪力槽中之流動行為，比較在不同外邊壁轉速下非球形顆粒體在剪力槽中之流動行為，並探討顆粒形狀對顆粒體在剪力槽中傳輸性質的影響，此外亦研究不同外邊壁轉速對顆粒體傳輸性質的影響。實驗採用的非球形顆粒體為短橢球形(顆粒長寬比為1.5)，長橢球形(顆粒長寬比為2.0)，膠囊形(顆粒長寬比為2.0)，及雙球形(顆粒長寬比為2.0)，採用卡氏粒子追蹤法量測顆粒體之平移速度，和改良式粒子追蹤法(Improved Particle Tracking Velocimetry)量測顆粒體之旋轉速度，進而計算相關的傳輸性質，包括切向速度，徑向速度、切向擾動速度，徑向擾動速度、旋轉擾動速度。在相同形狀顆粒體下比較五個轉速的速度曲線，曲線呈指數函數型態分佈，值得注意的是，雙球形就算在外邊壁低轉速時也能有很深的流動層厚度。不管在任何外壁轉速下，顆粒體在最外層的平均流速排序皆為球形> 雙球形> 膠囊形> 短橢球形> 長橢球形。綜合五個轉速觀察切向和徑向擾動速度分佈圖，發現同時比較偏移和平緩程度的排序皆為，膠囊形> 雙球形> 球形> 短橢球形> 長橢球形。 ;The purpose of the study is to investigate the flow behaviour of spherical and non-spherical particles in an annular shear cell, to compare the transport properties between them, and to explore the influence of particle shape on the flow behavior. This study also studies the granular flow behavior on the different rotational speeds of the outer wall. The granular materials used in the shear cell were ABS particles including spherical, ellipsoidal S (aspect ratio=1.5), ellipsoidal L (aspect ratio=2.0), capsule (aspect ratio=2.0) and paired particle (aspect ratio=2.0). The Voronoï imaging methods was employed to measure the translational velocities of the particles, and the Improved Particle Tracking Velocimetry (PTV) was employed to measure the rotational velocities of the particles. The transport properties of the particles in the shear cell, including the tangential velocity profile, the radial velocity profile, the fluctuation velocity distributions and the shear rate were analyzed. The tangential velocity profile decays roughly exponentially from outer wall. Although the paired particle were sheared by a low rotating speed of outer boundary, the flowing layer of the paired particle could extend thicker in the shear cell system. The magnitude of tangential velocity follows the sequence: spherical> paired> capsule> ellipsoidal S> ellipsoidal L. In the fluctuation distributions for the tangential and radial velocities, the flat degree follows the sequence: capsule> paired > spherical > ellipsoidal S > ellipsoidal L.
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