振動床運動機制之研究; Dynamic Behavior in a Vibrated Bed

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Title:	振動床運動機制之研究;Dynamic Behavior in a Vibrated Bed
Authors:	戴其璜;Chi-Hwang Tai
Contributors:	機械工程研究所
Keywords:	顆粒體;粒子溫度;自我擴散;擾動速度分佈;迴流胞;無因次迴流率;振動床;granular;granular temperature;self-diffusion
Date:	2001-07-14
Issue Date:	2009-09-21 11:36:41 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本論文運用實驗的方式探討顆粒體物質受到垂直振動時的動態行為。研究主題包括振動顆粒床體的迴流運動、顆粒體擾動速度分佈、整體粒子溫度及顆粒體自我擴散運動的探討。本文首先以實驗的方法，定性探討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振動顆粒床體振動加速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，由實驗結果顯示，自我擴散係數與振動參數如振動加速度、振動振幅與振動頻率的改變有重要的關係。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。 This thesis examines the dynamic behaviors of granular materials subjected to external vertical vibration. Experiment is used to study the flow behaviors,convection cell, fluctuating velovity distribution, granular temperature and self-diffusion of vibration granular flows. The flow behaviors of convection cells of granular materials under vertical vibration are first investigated by experiment. The flow pattern and velocity vectors are consistent with the former experimental results. The profiles of the granular temperatures with the altitude of granular bed are studied with different vibration conditions. The influences of flow parameters on self-diffusion in the vibrated granular bed are studied by 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 particles' 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 the greatest conponents in the vertical direction. The dependence of the diffusion coefficients on the dimensionless acceleration, vibration amplitude, vibration frequency, velocity fluctuations, and granular temperature are discussed carefully.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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