本文選題：大跨度橋梁 + 渦激共振��； 參考：《湖南大學》2015年碩士論文

【摘要】：大跨度橋梁是現(xiàn)代交通系統(tǒng)的重要基礎設施,世界正進入超大跨度橋梁建設的時代,而抗風性能是大跨度橋梁設計中關鍵問題之一。已有抗風設計方法已避免了災難性的顫振失穩(wěn)發(fā)生,但鋼箱梁橋的渦激共振問題是困擾抗風研究的一個重要問題。進行主梁剛性節(jié)段縮尺模型的彈性懸掛動力試驗是檢驗主梁渦振性能的常用手段。按風洞尺寸要求,節(jié)段模型的縮尺比在1/80~1/20左右。然而,已有的一些風洞試驗結(jié)果表明,模型縮尺比的不同會造成無量綱振幅有顯著差異。其作用機理尚不明確。本文在國家自然科學基金的資助下,以1:6矩形斷面對研究對象,對渦激共振的模型尺度效應進行了試驗研究,重點討論模型長寬比對渦振振幅、表面脈動壓力及其展向相關性的影響。本論文的主要工作如下:(1)介紹了顫振、馳振,抖振以及渦激振動的基本理論,重點并列舉了世界上幾個比較著名的橋梁渦激振動實例,同時簡述了本文的研究背景和內(nèi)容。(2)基于渦激振動的簡諧力模型闡述了影響渦振振幅的主要參數(shù),包括脈動升力系數(shù)、Strouhal數(shù)(St數(shù))、反映阻尼和質(zhì)量綜合效應的Scruton數(shù)(Sc數(shù))和渦激力的展向相關性。同時對氣動外形、雷諾數(shù)、來流湍流等影響上述參數(shù)的因素進行了分析。(3)設計制作了寬高比為6的一個大尺度模型(B=72cm,H=12cm)和兩個小尺度模型(B=40cm,H=6.7m)。大尺度模型長1.54m,相應的長寬比為2.14;小尺度模型長分別為1.54m和2.3m,相應的長寬比分別為3.85和5.75。進行了均勻流場中相同Sc數(shù)時的節(jié)段模型渦激共振測振試驗。結(jié)果表明,三個試驗模型均出現(xiàn)了兩個明顯的渦激振動區(qū)間,第二渦激振動區(qū)間的最大振幅大于第一渦激振動區(qū)間的最大振幅。且兩個小尺度模型的最大無量綱振幅基本相同,大尺度模型最大無量綱振幅約只有兩個小尺度模型的最大無量綱振幅的一半。(4)對三個模型表面壓力系數(shù)均方差、升力系數(shù)均方差以及相同無量綱振幅下的升力展向相關性進行了研究,結(jié)果表明L/B=2.14的大尺度模型的表面壓力系數(shù)均方差、升力系數(shù)均方差及升力展向相關性要明顯小于兩個小尺度模型(L/B=3.85,L/B=5.75)的表面壓力系數(shù)均方差、升力系數(shù)均方差以及升力展向相關性,同時對振幅以及紊流對于展向相關性的影響也進行了研究。(5)利用CFD對小尺度短模型進行了二維數(shù)值模擬,并與試驗結(jié)果進行對比,渦振鎖定區(qū)間與試驗結(jié)果基本吻合,第二渦激振動區(qū)間最大無量綱振幅略有差異。
[Abstract]:The large span bridge is an important infrastructure of the modern traffic system, the world is entering the era of the construction of the super long span bridge, and the wind resistance is one of the key problems in the design of the long-span bridge. The wind resistance design method has avoided the catastrophic flutter instability, but the problem of the vortex resonance of the steel box girder bridge is one of the research of wind resistance. The elastic suspension dynamic test of the rigid segment model of the main beam is a common method to test the vortex vibration performance of the main beam. According to the size of the wind tunnel, the scale ratio of the segment model is about 1/80~1/20. However, some wind tunnel test results have shown that the difference in the scale ratio of the model will cause a significant difference in the dimensionless amplitude. The mechanism of its action is not clear. Under the support of the National Natural Science Foundation of China, this paper studies the model scale effect of the vortex excited resonance (SR) on the 1:6 rectangular section, and focuses on the influence of the length width ratio of the model to the amplitude of the vortex vibration, the surface pulsation pressure and its spreading correlation. The main work of this paper is as follows: (1) The basic theories of flutter, galloping, buffeting and vortex induced vibration are discussed, and several famous examples of vortex excited vibration in the world are listed, and the research background and content of this paper are briefly described. (2) the main parameters affecting the amplitude of vortex vibration, including pulsating lift coefficient, Strouhal number (St), are described. The number of Scruton numbers (Sc numbers) reflecting the comprehensive effect of damping and mass and the extension correlation of the vortex excitation are analyzed. The factors affecting the parameters such as aerodynamic shape, Reynolds number and flow turbulence are analyzed. (3) a large scale model (B= 72cm, H=12cm) and two small scale models (B=40cm, H=6.7m) are designed and made in large scale. The model length 1.54M, the corresponding length and width ratio is 2.14, the small scale model length is 1.54M and 2.3m respectively, the corresponding length width ratio is 3.85 and 5.75. respectively. The section model vortex induced resonance vibration resonance vibration test of the same Sc number in the uniform flow field is carried out. The results show that the three experimental models have two distinct vortex vibration intervals and second vortex excited vibration intervals. The maximum amplitude is greater than the maximum amplitude of the first vortex excited vibration interval. And the maximum dimensionless amplitude of the two small scale models is basically the same, and the maximum dimensionless amplitude of the large scale model is about half of the maximum dimensionless amplitude of the two small scale models. (4) the mean square variance of the pressure coefficient of the surface of the three models, the mean square deviation of the lift coefficient and the phase The correlation of the lift extension under the dimensionless amplitude is studied. The results show that the mean square variance of the surface pressure coefficient, the mean square deviation of the lift coefficient and the upward trend of the lift force in the large scale model of L/B=2.14 are obviously smaller than the mean square variance of the surface pressure coefficient of the two small scale models (L/B=3.85, L/B=5.75), the mean square deviation of the lift coefficient and the lift extension. The influence of the amplitude and turbulence on the extension correlation is also studied. (5) the two-dimensional numerical simulation of the small scale short model is carried out by CFD. The results are compared with the experimental results. The locking interval of the vortex vibration is basically consistent with the experimental results, and the maximum dimensionless amplitude of the second vortex excited vibration interval is slightly different.

【學位授予單位】：湖南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U441.3

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本文編號：1870194