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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/43579


    Title: 非球形顆粒體在振動床中流動行為之研究;An investgation of the flow behaviour of non-spherical particles in vibrating beds.
    Authors: 吳俊輝;Chun-Hui Wu
    Contributors: 機械工程研究所
    Keywords: 改良式粒子追蹤法;振動條件;顆粒體輸送性質;非球形顆粒;振動床實驗;Transport property;Vibration conditions;Improved PTV;Vibrated bed;Non-spherical particulate system
    Date: 2010-08-17
    Issue Date: 2010-12-08 13:45:41 (UTC+8)
    Publisher: 國立中央大學
    Abstract:   本文旨在研究非球形顆粒體在振動床中之流動行為,探討振動條件(振動加速度與頻率)對非球形顆粒體輸送性質之影響,並比較在相同振動條件下球形與非球形顆粒體在振動床中之流動行為。實驗採用的非球形顆粒體為雙球形體顆粒,係由兩顆尺寸相同之POM球形顆粒黏接而成。本研究採用改良式粒子追蹤法(Improved Particle Tracking Velocimetry)量測雙球形顆粒體之平移速度及旋轉速度,進而計算顆粒體輸送性質(例如:局部平均速度、局部擾動速度、局部粒子溫度、擾動速度分佈、擴散係數、無因次質量流率及整體粒子溫度與整體平均動能)。研究結果顯示改良式粒子追蹤法能精確地量測振動床中雙球形顆粒體的平移速度及旋轉速度。本研究展示雙球形顆粒體之迴流現象,另由旋轉擾動速度分佈得知顆粒旋轉在振動床中頗為顯著。   在固定振動頻率下,雙球形顆粒體的平移速度或旋轉速度皆隨著無因次振動加速度的增加而增加,顆粒體間之碰撞增加,進而增加顆粒體擾動速度,以致擾動速度分佈趨於扁平。同時,雙球形顆粒體的無因次質量流率隨著無因次振動加速度與振動速度之增加而增加。同樣地,整體粒子溫度隨著無因次振動加速度與振動速度之增加而增加。雙球形顆粒體的無因次質量流率亦隨著整體粒子溫度之增加而增加。在相同振動條件下,球形顆粒體之無因次質量流率與整體粒子溫度皆高於雙球形顆粒體之無因次質量流率與整體粒子溫度,此乃雙球形顆粒體之間產生互鎖效應,降低無因次質量流率與整體粒子溫度。  This thesis investigates the flow behaviour of non-spherical particles in vibrating beds, studies the influence of vibration conditions on the flow behaviours and compares the flow behaviour between spherical and non-spherical particles. At the preliminary tests, paired POM particles (one of the non-spherical particles), made by gluing two single POM beads, were studied. The improved Particle Tracking Velocimetry (PTV) was employed to measure the translational and rotational velocities of these non-spherical particles in a vibrating bed. The transport properties of the paired POM particles in a vibrated bed, such as local average velocities, local fluctuation velocities, granular temperatures, fluctuation velocity distributions, self-diffusion coefficients and dimensionless convection flow rates, were evaluated from the experimental results and discussed. The study has shown that the improved PTV technique has the ability to measure more accurately the velocity field of non-spherical particulate systems and that the particle rotation can play a significant role in a vibrated granular bed.  The dimensionless convection flow rates and global granular temperatures in the non-spherical granular vibrated bed increase with the increase of the vibration acceleration and velocity. The dimensionless convection flow rates also increase with increasing the global granular temperatures. The dimensionless convection flow rates and global granular temperatures in a spherical granular system are larger than those in a non-spherical granular system since the POM paired particles studied here induce a particle inter-locking than spherical particles.
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