Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/13725
標題: 圓柱近域尾流場特性之實驗研究
AN EXPERIMENTAL STUDY ON THE FLOW CHARACTERISTICS IN THE NEAR WAKE OF A CIRCULAR CYLINDER
作者: 方明仁
Ren, Fang Ming
關鍵字: Taylor hypothesis;泰勒假設;Organized structure;convection speed;組織結構;渦心平均移動速度
出版社: 土木工程研究所
摘要: 
本文旨在應用流場可視化及併用一維 He-Ne LDV測速儀及二維Ar+ LDV 測
速儀,於不同自由流速下,探討圓形柱體近域尾流場之特性。文中可視化
法係採用染液注入法以觀察流場中煙線之變化,藉以提供一定性之分析。
至於 LDV 定量量測部份之,特以一維LDV作為攫取流場中具相位關聯性結
構的參考基準,從而剖析流場及其組織結構之特性。再利用修正相位平均
法來分析條件取樣之數據。文中對於圓柱尾流場之現象觀察、平均流場特
性、速度頻譜特性、渦心移動特性、速度相位變化、渦度相位變化及應力
相位變化等均有詳細討論。

The flow characteristics in the near field of a circular
cylinder were conducted experimentally at Reynolds
number, according to the cylinder diameter, between 400 and
12000 by using flow visualization techniques and conditional
sampling. Experimental measurements were made in a water
channel at several sections downstream by two precise laser
Doppler velocimeter systems (LDV). Velocity fluctuations
were decomposed into the phase-averaged organized wave
component and irregular fluctuation, then the actual
distributions of the vortex structure properties have been
obtained through this phase-averaged data. In addition,
based on the peak of the space-time correlation of the
fluctuation, yield the variation of vortex convection speed
along the vortex trajectory. Based on the analysis of this
study, the following objectives were discussed: (1)the
variation of vortex convection speed (2)the phase velocity
vector field (3)the applicability of the Taylor hypothesis
(4)the topology of the organized structure motion (5) the
contours of the stresses fields.
URI: http://hdl.handle.net/11455/13725
Appears in Collections:土木工程學系所

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