粉粒體內摩擦係數對剪力顆粒流輸送性質之影響; Effect of internal friction angle of particles on transport properties of sheared granular flows.

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题名:	粉粒體內摩擦係數對剪力顆粒流輸送性質之影響;Effect of internal friction angle of particles on transport properties of sheared granular flows.
作者:	許智淵;jr-yuan shiu
贡献者:	機械工程研究所
关键词:	粒子自我擴散係數;顆粒流;剪力槽;粒子間內摩擦係數;壓力規;granular flow;internal friction coefficient;stress gage;shear cell;self-diffusion coefficient
日期:	2004-07-05
上传时间:	2009-09-21 11:46:36 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	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.
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