振動床內顆粒運動之研究; A study of the granular motion in a vibrated bed

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Title:	振動床內顆粒運動之研究;A study of the granular motion in a vibrated bed
Authors:	戴世璋;Shih-Chang Tai
Contributors:	機械工程研究所
Keywords:	振動速度;類液體狀態;過渡區;類固體狀態;粒子佔有體積;顆粒層高度;solid fraction;vibration velocity;liquid-like state;transition region;solid-like state;dimensionless depth of the granular layer
Date:	2009-07-22
Issue Date:	2009-09-21 11:52:54 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本論文探討二維及三維顆粒物質受到垂直振動時的運動狀態行為，本研究利用“凍結(jelled)”取樣的方法，在不使用昂貴的儀器操作下，有效計算三維振動顆粒床在不同振動條件下的顆粒分佈情形，並探討顆粒床自由表面的粒子運動行為和顆粒床內的流動轉換機制，藉由床體內粒子能量變化定義振動顆粒床的三種狀態行為:類固體狀態、過渡區和類液體狀態，當振動顆粒床的運動狀態從類固體狀態進入類液體狀態過程，顆粒床內的運動機制會由顆粒重組機制轉換為表面對流機制。在二維振動顆粒床方面，本研究討論不同振動參數對垂直顆粒床粒子運動的影響，發現振動速度越大、粒子佔有體積越小、顆粒層高度越低，會使得振動顆粒運動越劇烈，且在特別條件下，可以使得容器上壁能有效加強顆粒的運動。 The dynamic behavior and the motion state of two-dimensional and three-dimensional granular materials subjected to external vibration were investigated. Sampling of a granular bed which had “jelled” at a steady state allowed for examination of the particle distributions inside the three-dimensional granular bed at different vibration conditions without involving expensive instruments. And the granular motion at the free surface of a vibrated bed and the transition of the flow regimes inside the bed could both be investigated. We studied the variation in the granular kinetic energy at the free surface of the three-dimensional vibrated bed under different vibration conditions. The variation in the energy defined the following motion states: solid-like state, transition region and liquid-like state. The movement mechanism inside the granular bed was transformed from particle reorganization to surface convection as the bed state transferred from a solid-like state to a liquid-like state. The influence of the vibration parameters on the granular motion of a two-dimensional vibrated granular bed was probed. It was found that the motion of the vibrated particles became stronger with the increase of dimensionless vibration velocity, the decrease of the solid fraction and the decrease of the dimensionless depth of the granular layer. Furthermore the upper-boundary of the container strengthened granular motion under some specific conditions.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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