臺灣博碩士論文加值系統

本論文將以實驗方法，對粉粒體內摩擦係數於剪力槽內之應力與傳輸現象做分析。改變變因為不同粒子間內摩擦係數值μp之顆粒體以及不同粒子佔有體積比ν，以擷取影像計算的方式來取得不同粒子之平均速度分布、變動速度分布、粒子溫度分布、粒子擴散位移以及粒子擴散係數。並利用置於剪力槽上壁面三個雙向壓力規，量測剪應力值與正向應力值，用於分析作用於剪力槽邊壁之作用力。
在相同條件下，正向應力值皆大於所測得的剪應力值。在固定粒子佔有體積比ν中，粒子間內摩擦係數µp較小，其正向應力值與剪應力值會越大。隨著粒子佔有體積比ν的提高，量測得的正向應力值與剪應力值會越大。隨著粒子佔有體積比ν的變化，粒子間的內摩擦係數µp較大者對於應力的影響也較大。
粒子間內摩擦係數µp越大，Dxx與Dyy 值越小。Dxx與Dyy其值隨粒子佔有體積比ν的提高而減少。在較低的粒子佔有體積比ν中，粒子間內摩擦係數µp所造成Dxx與Dyy的差異會大於在高粒子佔有體積比ν中。

We have studied the effect of internal friction coefficient of particles on transport properties of sheared granular flows. Experiments were performed in shear cell device under four different internal friction coefficients of the particles and five different solid fractions. The motions of the granular materials were recorded by a high-speed camera. By using image processing technology and particle tracking method, we measured and analyzed the distributions of the average velocity, fluctuation velocity, granular temperature, and particle self-diffusion coefficient. Three bi-directional stress gages were used to measure the normal and shear stresses along upper boundary.

According to the experimental results, the stresses and the self-diffusion coefficients of the particles were inverse the internal friction coefficients. In the same conditions, the normal stresses were apparently higher than the shear stresses. The fluctuation and the self-diffusion coefficients in the streamwise direction were obviously higher than those in the transverse direction. The normal and shear stresses were found to increase with the solid fraction, but the diffusion coefficients were greater in a more dilute flow system. While the particles of the shear flows were in low solid fraction condition, the stresses and self-diffusion coefficients were much different than those in high solid fraction condition.

目錄

摘 要 i
Abstract ii
目 錄 iii
附表目錄 v
附圖目錄 vi
符號說明 x

第一章 簡介 1
1.1粒子流簡介 1
1.2剪力粒子流的研究歷史 4
1.3研究方向與架構 12
第二章 實驗方法 14
2.1 實驗設備 14
一、剪力槽裝置 14
二、顆粒體 16
三、觀測及量測儀器 17
2.2 實驗原理與方法 21
一、Correlation簡介 21
二、Correlation程式流程 23
2.3 粒子溫度之概念 26
2.4 剪力槽內剪應力分析 27
2.5 自我擴散理論 28
2.6 實驗步驟 30
2.7 誤差校正 34
一、誤差來源 34
二、誤差校正(Calibration) 35
第三章 結果與討論 37
3.1速度曲線分布圖與粒子溫度分布圖 37
3.2剪力槽內應力分析 44
3.3粒子擴散位移與擴散係數 47
第四章 結論 52
參考文獻 54

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