液體對振動床內運動機制之影響; The effect of liquid on dynamic mechanism in granular vibrated bed

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题名:	液體對振動床內運動機制之影響;The effect of liquid on dynamic mechanism in granular vibrated bed
作者:	王啟毓;Chi-Yu Wang
贡献者:	機械工程研究所
关键词:	能量消散;液橋;振動床;顆粒流;Energy dissipation;Granular flow;Liquid bridge;Vibrated bed
日期:	2006-07-07
上传时间:	2009-09-21 11:55:03 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本文運用實驗的方式探討顆粒體在垂直振動床內，不同的液體含量、表面張力和黏度對其動態行為的影響。研究主題包括不同的液體條件下對振動顆粒床體的迴流運動、整體粒子溫度、顆粒體擾動速度分佈及粒子自我擴散運動的探討。　　本文首先以實驗的方法，定性探討附著性顆粒振動床的迴流運動現象，實驗結果與相關文獻的實驗結果比較，頗為符合；進一步以定量的觀點分析顆粒間液體含量、表面張力、黏度與粒子溫度的關係，同時計算迴流中心質量流率的大小。接著，以實驗的方法討論顆粒體擾動速度分佈及顆粒體振動床的自我擴散運動，粒子自我擴散運動乃是經由粒子間持續碰撞運動的變動速度所產生。在實驗方面，應用影像處理技術及粒子追蹤的方法，可準確量測並計算出追蹤粒子的位置與速度大小，藉由追蹤粒子的擴散位移與時間的關係可計算出粒子的自我擴散係數。此外，振動床體平均變動速度、粒子溫度的大小與自我擴散係數，由於受到垂直振動外力的影響，呈現非等向性分佈，在垂直方向分量大於水平方向分量，相關的研究在本文中均有深入的探討。關於含有液體的顆粒體，文中以不同液體黏度、表面張力和液體添加量的ㄧ百二十組實驗做為分析對象，來探討顆粒體間液橋力對顆粒體動態行為的影響。當顆粒體受垂直振動力的作用時，床體能量會因為某些因素的的影響而消散，包括粒子間的摩擦阻力與非完全彈性碰撞、黏性液橋力的黏滯阻力與毛細結合力等。由實驗結果顯示，在固定振動條件下，能量的消散主要來自於液體液橋力的黏滯阻力，毛細力的影響較不明顯，能量消散的大小並隨著粒子間液體多寡的增加而增加。 This thesis examines the dynamic behaviors of granular materials subjected to external vertical vibration. The cohesive materials are considered in this thesis. Two-dimensional experiment method is used to study the flow behaviors when we added different liquid content, different viscous liquids and liquids of different surface tension. The flow behaviors of convection cells of cohesive materials under vertical vibration are first investigated by experiment method. The results are consistent with the former experimental results. The convection flow rate and the granular temperatures are studied with different liquid content, different viscous liquids and liquids of different surface tension . The influences of flow parameters on self-diffusion in the vibrated granular bed are studied by simulation and experiment. Employing the image processing technology and particle tracking method, the local displacements and velocities of particles are measured. The self-diffusion coefficients are determined from the history of particle’s diffusive displacements. The flow behaviors of convection cell are strongly related to the self-diffusion of particles induced by the energy input from the vertical external vibration. The velocity fluctuations, granular temperature and self-diffusions are anisotropic with greatest components in the vertical direction. The self-diffusion coefficients and the granular temperature are discussed carefully. One hundred twenty types of liquids with different liquid content, different viscous liquids and liquids of different surface tension are used in this thesis. The effect of liquid bridge force with particle dynamic behavior are studied in this paper. The energy dissipations during vertical vibration are generated from the friction and inelasticity between particles, viscous resistance and liquid bridge bond rupture due to the liquid bridge. For cohesive granular materials, the energy dissipation is mainly associated with the viscous force, the interparticle friction and the inelasticity of collision, rather than with the capillary force of liquid bridge. The results of experiment reveals that the energy dissipation caused by viscous force are larger than capillary force. The energy dissipation increases monotonously with the increase of the dimensionless interstitial liquid volume, and the dissipation are strongly influenced by the properties of viscous liquids.
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