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標題: | 沉浸單擺運動與第二固體邊界之流體耦合距離之研究 Hydrodynamic Coupling Distance for an Immersed Pendulum Approaching Toward a Nearby Solid Boundary |
作者: | You-Yuan Zheng 鄭又元 |
指導教授: | 楊馥菱 |
關鍵字: | 沉浸單擺運動,流體耦合距離,邊界效應,顆粒流,黏性流, immersed pendulum motion,hydrodynamic coupling distance,boundary effects,granular flow,viscous flow, |
出版年 : | 2011 |
學位: | 碩士 |
摘要: | 本論文以實驗探討非穩態沉浸單擺運動如何受下游第二邊界影響而減速,所考慮的目標物為尺寸大小不同的球體及平板,藉由改變單擺擺角、密度及甘油水溶液的黏度及密度來達到不同擺球雷諾數(Re)及史托克數(St)。以高速攝影機擷取之實驗影像利用霍夫轉換求出球體中心位置之時間序列,並進一步算出擺球於不同球面間距時之擺球速度。本論文更進一步量取同擺球、擺角及液體卻無下游目標物的自由沉浸單擺運動以此為基準,以擺球受下游目標物影響速度下降5%之位置定義兩球面之耦合距離。研究發現此耦合距離隨Re及St之下降上升,而相同Re及St下目標物尺寸上升時耦合距離亦上升。 This research examines the unsteady pendulum motion in viscous fluid with the presence of a second solid boundary with high-speed imaging technique. It is observed that when a pendulum moves perpendicularly towards a solid boundary, the pendulum velocity decelerates before contact. A hydrodynamic coupling distance is proposed in this work to characterize the degree of influence of a second stationary target on the immersed pendulum motion. This coupling distance is observed to increase monotonically with diminishing pendulum Reynolds number (Re) and Stokes number (St) and with the target size. In the experiments, a range of Re and St were achieved by using different pendulum size, release angle, particle and liquid densities. The captured high-speed image sequence was processed by Circular Hough Transform method to locate the incident sphere center which was further employed to estimate pendulum velocity. The pendulum motion was normalized by a free pendulum motion generated using identical pendulum, liquid, and release angle but without the presence of a second solid boundary. The location where the two pendulum motion deviate from each other is used to define the so-called hydrodynamic coupling distance. Afterwards, we apply Non-dimensionalize methods to compare the free pendulum with the one that influence by a solid boundary. Thus, the coupling distance is found by estimating the decreasing rate of the velocity. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/48089 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
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