Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1483
標題: 縱列與錯列雙圓柱尾流結構之實驗分析
Experimental Analysis on Wake Characteristics behind Two Cylinders in Tandem and Staggered Arrangements
作者: 簡賢明
Chian, Hsian-Ming
關鍵字: tandem;縱列;staggered;cavity mode;narrow wake;wide wake;錯列;雙圓柱;空穴剪力層
出版社: 機械工程學系
摘要: 
摘要
本研究係應用螢光染液釋放法進行流場可視化,以及雷射杜普勒測速儀量測速度及頻譜能量特性,探討在雷諾數Re=1000的條件下,縱向排列與交錯排列的雙圓柱尾流場之結構特性。從而深入瞭解控制圓柱在不同位置時,對於主要圓柱尾流場的影響,並依流場中特徵頻率之變化加以詳細分類。實驗結果可分為三大部分:
(1).當兩縱列圓柱(Yc/D=0)的流向間距為:(a)Xc/D=1.5~3.5時,兩圓柱間的流場形成平順剪力層。(b)Xc/D=3.5~5.5時,兩圓柱間的流場形成空穴剪力層結構。(c)Xc/D≧6.0時,兩圓柱間的流場恢復成為交替脫離的渦漩結構。
(2).當兩錯列圓柱(Yc/D=0.5)的流向間距為:(a)Xc/D=1.0∼3.0時,兩圓柱間的上、下方剪力層因偏向流的關係,形成合流剪力層結構。(b) Xc/D=3.5∼5.0時,兩圓柱間的流場形成上側為空穴剪力層結構,而下側為單一渦漩結構。(c)Xc/D≧5.5時,兩圓柱間的流場恢復成為交替脫離的渦漩結構。
(3).當兩錯列圓柱(Yc/D=1.0)的流向間距為:(a)Xc/D=1.0~4.0時,兩圓柱間形成窄域尾流場。(b) Xc/D≧4.5時,兩圓柱間的流場恢復成為交替脫離的渦漩結構。

The wake characteristics between two cylinders in tandem and staggered arrangements are investigated at a Reynolds number of 1000 by the flow visualization and the velocity measurement. Quantitative velocity measurement and quantitative flow visualization were performed by ways of LDA system and laser sheet technique. Some important results are concluded as follows:
(1) In case of tandem arrangement(Yc/D=0), the flow are classified into three different characteristics. They are: (a) smooth shear layers between two cylinders as the streamwise spacing (Xc/D) is between 1.5~3.5. (b) when the streamwise spacing (Xc/D) is around 4.0~5.5, the flow characteristic between two cylinders becomes the cavity mode. (c) as the streamwise spacing (Xc/D) is larger than 6.0, the flow structure between two cylinders becomes an alternate shedding vortex street.
(2) In staggered arrangement (Yc/D=0.5), three kinds of flow characteristics are found as follows: (a) as the streamwise spacing (Xc/D) ranges between 1.0 and 3.0, the impinging shear layer is stably deflected downward, interacting with the lower shear layer and shedding downstream. (b) as the streamwise spacing (Xc/D) is around 3.5~5.0, the impinging shear layer becomes cavity mode and the other free shear layer rolls up and sheds downstream. (c) as the streamwise spacing (Xc/D) is larger than 5.5, the flow structure between two cylinders becomes an alternate shedding vortex street.
(3) In staggered arrangement (Yc/D=1.0), two different flow characterics are concluded as follows: (a) as the streamwise spacing (Xc/D) is around 1.0~4.0, the deflected gap flow between two cylinders leads to the narrow wake behind the main cylinder and wide wake behind the control cylinder. (b) as the streamwise spacing (Xc/D) is larger than 4.5, the flow structures behind two cylinders become two independent vortex streets.
URI: http://hdl.handle.net/11455/1483
Appears in Collections:機械工程學系所

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