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    請使用永久網址來引用或連結此文件: http://ir.lib.ncu.edu.tw/handle/987654321/75330


    題名: 以物理實驗探討顆粒形狀 對顆粒體在旋轉鼓中傳輸性質的影響
    作者: 羅敏夫;Lo, Min-Fu
    貢獻者: 機械工程學系
    關鍵詞: 非球形顆粒體;旋轉鼓試驗;形狀效應;傳輸性質;non-spherical particles;rotating drum test;shape effect;transport properties
    日期: 2017-10-24
    上傳時間: 2018-01-16 11:07:10 (UTC+8)
    出版者: 國立中央大學
    摘要: 本研究藉由改良式粒子追蹤影像處理技術探討非球形顆粒體在類二維旋轉鼓的流動行為,並探討不同轉速及填充率下,顆粒形狀對顆粒體在旋轉鼓中傳輸性質的影響,其中傳輸性質包含平移速度向量場、旋轉速度向量場、流動方向速度沿深度方向分佈、擾動速度分佈、擴散位移、粒子溫度及平均動能。本研究使用的顆粒為包含膠囊形(長寬比2.0)、橢球Ⅰ形(長寬比1.5)、橢球Ⅱ形(長寬比2.0)、雙球形(長寬比2.0)及球形顆粒,根據實驗結果顯示,本研究中所有受載條件下,被動層的流動行為與顆粒形狀較無明顯關係,而主動層表面流線以球形顆粒最為曲折且陡峭,顯示出球形顆粒之間歇性崩塌最為顯著。五種顆粒在受載條件為4rpm-50%時,流動方向擾動速度分佈皆呈現峰值左移的現象,垂直流動方向擾動速度分佈則趨勢相近,而旋轉方向擾動速度分佈皆呈現左右對稱,且旋轉方向擾動速度的峰值與顆粒互鎖效應(inter-locking effect)有密切關係,此外平均平移動能以球形最高,在探討的非球形顆粒體中,平均旋轉動能則以橢球Ⅰ形最高。當旋轉鼓為低轉速時易產生間歇性崩塌,流動方向的擾動速度分佈僅在旋轉鼓轉速為1rpm時為馬克士威爾分佈,其餘較大轉速則有左移的現象,垂直流動方向的擾動速度分佈皆呈現馬克士威爾分佈,旋轉方向的擾動速度分佈皆呈現左右對稱,此外流動方向與垂直流動方向的擴散位移皆以球形有最大的擴散係數。填充率對傳輸性質沒有明顯的影響,此外本研究觀察得知,橢球Ⅱ形的崩塌行為呈現搖擺式運動,細長扁平顆粒易於在崩塌時呈現上下搖擺的運動行為。;The purpose of this study is to experimentally investigate dynamic behavior of non-spherical particles in a qusi-2D rotating drum. The effect of particle shape on flow behavior of granular assembly were explored. The dependence of transport properties on rotating speed and filling degree was also evaluated. The granular materials used in the experiment included capsule particles (aspect ratio = 2.0), ellipsoidal particlesⅠ(aspect ratio = 1.5), ellipsoidal particlesⅡ(aspect ratio = 2.0), paired particles (aspect ratio = 2.0) and spherical particles. Improved Particle Tracking Velocimetry was employed to measure translational and rotational velocities of non-spherical particles. The transport properties, such as the local average velocities, the stream-wise velocity profiles, the distributions of fluctuation velocity, diffusive displacement, granular temperature and average kinetic energy were analyzed and discussed in the thesis. The results show that the particle shape does not influence the behavior of granular assembly in the passive layer, and that spherical particles exhibit the obvious waver motion under all loading conditions. When the loading condition is 4rpm-50%, the fluctuation velocities in the flow direction show asymmetric distributions for five kinds of particles. The distributions of fluctuation velocity perpendicular to the flow direction are close between them. The distributions of rotational fluctuation velocity show symmetric patterns and salient difference resulting from particle shapes. As the rotating speed decreases, the intermittent avalanche becomes more obvious, and the fluctuation velocity distribution exhibits the same trend except 1 rpm. Filling degree has slight effect on transport properties。In addition, the avalanche of ellipsoidal particlesⅡ shows waver motion.
    顯示於類別:[機械工程研究所] 博碩士論文

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