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研究生: 余文正
Wen-cheng Yu
論文名稱: 二維剪力槽不同邊壁運動形式粒子動態行為之研究
The effect of different rotational types on dynamics properties in a two-dimensional sheared granular flows.
指導教授: 蕭述三
Shu-san Hsiau
口試委員:
學位類別: 碩士
Master
系所名稱: 工學院 - 機械工程學系
Department of Mechanical Engineering
畢業學年度: 99
語文別: 中文
論文頁數: 105
中文關鍵詞: 粒子流環型剪力槽邊壁運動形式切向速度局部粒子占有率
外文關鍵詞: Tangential velocity, Rotational types, Annular shear cell, Granular flow, Local solid fraction
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  • 在傳統流體力學裡,一般流體的流動為連續運動,由微觀的角度來看,流體流動分子間的相對位移不超過一個特徵長度。而在粒子流的領域裡,粒子的流動屬於不連續運動,受到粒子間吸引力較為薄弱的影響,粒子間的相對位移大於一個特徵長度。在流體動力學中,那維爾-史托克方程式常用來描述黏性流體在平板、斜管等不同環境下的流體運動。在粒子流中,粒子受到外界能量的作用下,粒子群的型態可以像固體、液體和氣體般的狀態存在,並且可以以多相的形態存在。因此,由於粒子間複雜的碰撞行為,一般的理論方程不適用於描述粒子的運動行為。
    在本篇論文中,探討在二維環型剪力槽中,不同邊壁運動形式對於粒子動態行為的影響。在內、外邊壁單獨轉動系統中,由實驗結果可得知,粒子受到剪力的作用下,粒子切向速度以類指數型態分佈,隨著和剪力邊壁距離的增加,粒子切向速度呈現遞減的分佈。在相同邊壁速度參數下,因不同局部占有率的影響,在外邊壁轉動的系統中,接近剪力邊壁處有較高的局部粒子占有率,因此存在較大的切向速度值。在本論文中,也將探討內、外邊壁同時同向和反向運動,對於粒子動態行為的影響。


    In fluid dynamics, liquid flow is continuous flow. In microcosmic, the relative displacement is not yet one characteristic length. In granular flow, the flow is not continuous flow, the weak attraction around particle will let relative placement over one characteristic length. In fluid dynamics, Navier-Stokes equation is usually used to describe the flow behaviors in tube flow, plate flow and draft flow. In granular flow, multiphase flow behaviors may exist as granular materials are driven by external force. Granular materials may behave solid, liquid and gas depending on the processing conditions. Thus, general theory is still poor to describe the granular flows due to the complex flow behavior.
    In this thesis, the two-dimensional annular shear cell is used to investigate the dynamic properties of granular flow with different rotational types. Through experiment analyze, we know the velocity profile is roughly exponential decay from shearing boundary with only inner wall or outer wall rotation. The tangential velocity of particles with rotating outer boundary is larger than rotating inner boundary under the same rotating tangential velocity. Pass by analyze, the results show that the local solid fraction is different near inner and outer shear boundary, particles collision violently when solid fraction is higher. In this thesis, we also discuss the flow behaviors by rotating both walls with the same direction rotation and inverse direction rotation.

    摘要 i 附表目錄 vi 第一章 簡介 1 1.1粒子流簡介 1 1.1.1顆粒體介紹 1 1.1.2粒子流與一般流體之異同 2 1.1.3粒子流的研究發展 4 1.1.4剪力粒子流的研究歷史 7 1.2研究動機與架構 11 第二章 實驗方法與原理 12 2.1實驗設備 12 2.1.1剪力槽 12 2.1.2顆粒體 14 2.1.3觀測及量測儀器 15 2.2實驗方法及原理 16 2.2.1粒子溫度概念 16 2.2.2影像處理分析方法 18 2.2.3分析參數 19 2.3實驗步驟 21 2.4實驗誤差 24 2.4.1誤差來源 24 2.4.2實際速度與程式分析速度之比較 24 第三章 結果與討論 26 (一) 內、外邊壁單獨轉動實驗 26 3.1固定粒子占有率,探討切向速度分佈與邊壁速度變化之關係 26 3.1.1內邊壁單獨轉動 26 3.1.2外邊壁單獨轉動 27 3.2固定邊壁速度,探討粒子切向速度分佈和粒子占有率變化之關係 28 3.2.1內邊壁單獨轉動 28 3.2.2外邊壁單獨轉動 29 3.3相同內、外邊壁速度,平均切向速度之比較 30 3.4邊壁速度和粒子占有率對於滑移速度變化之影響 31 3.4.1內邊壁單獨轉動 31 3.4.2外邊壁單獨轉動 31 3.5固定粒子占有率,內、外邊壁轉動對滑移速度變化之比較 32 3.5.1粒子滑移速度和邊壁速度變化關係 32 3.5.2粒子滑移速度於內、外邊壁轉動效應之比較 33 3.5.3不同粒子占有率對於內、外邊壁滑移效應之影響 33 3.6粒子溫度 34 3.6.1固定粒子占有率,粒子溫度和邊壁速度變化之關係 34 3.6.2固定邊壁速度,粒子溫度和粒子占有率變化之關係 34 (二) 內、外邊壁同時轉動對顆粒動態行為的影響 35 3.7內外邊壁同方向、反方向轉動,切向速度間的相異性 35 3.8內外邊壁同方向、反方向轉動,粒子溫度間的相異性 36 3.9內外邊壁同方向、反方向轉動,局部粒子占有率間的相異性 37 第四章 結論 38 (一) 內、外邊壁單獨轉動實驗 38 (二) 內、外邊壁同時轉動實驗 39 參考文獻 40

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