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題名 | 改善二維圓柱尾流邊端效應之新法=New Method to Avoid End-Effects on the Wake of Circular Cylinder at Low Reynolds Numbers |
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作者 | 王安邦; 王炫証; 郭仕衡; Wang, An-bang; Wang, Hsuan-cheng; Kuo, Shih-heng; |
期刊 | 中國土木水利工程學刊 |
出版日期 | 19981200 |
卷期 | 10:4 1998.12[民87.12] |
頁次 | 頁753-758 |
分類號 | 440.137 |
語文 | chi |
關鍵詞 | 邊端效應; 二維圓柱; 渦漩剝離; End effects; Circular cylinder; Vortex shedding; |
中文摘要 | 在低雷諾數下(Re=50~160),二維圓柱尾流很容易受到邊端固定條件影響而產生 尾流特性的改變,諸如尾流的三維性、臨界雷諾數的變化,此即一般所謂之「邊端效應」。 本文主要目的即在設計、探討一種新式而簡單的支撐法,利用流體力學之特性,以解決此種 在實驗流體力學文獻中存在已久,但一直尚未真正解決的困擾。本文中以實驗證實:吾人所 發展之新支撐法,可非常有效地改善二維圓柱邊端所引致的三效維應,使其尾流能保持二維 平行模式, 在雷諾數小於 170 之範圍內,史卓荷數對雷諾數之關係曲線無不連續之產生。 另外,此新支撐法同時顯示具有臨界雷諾數不再敏感於圓柱展弦比之優越性。此新支撐法理 想之參考設計值為:錐形柱之錐度比≦ 20,支撐長度值≧ 10 倍二維圓柱直徑。 |
英文摘要 | Even in ideal conditions, the vortex shedding from the cylinder may become three-dimensional due to the end effects for Re=50~160. In this paper, a newly developed tapered beam and plate method has been designed to minimize the end effects of the circular cylinder, which has been tested to be very useful. The experimental results show that the tapered supportbeam should have a taper ratio no larger than 20 and a length no less than 10 times the cylinder diameters. The proposed support method is superior in that it may keep not only the wake flow maintaining parallel mode, but the critical Reynolds number almost independent of the aspect ratio of the circular cylinder. |
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