1:6矩形断面涡激共振的模型尺度效应试验研究

发布时间：2018-05-10 17:22

本文选题：大跨度桥梁 + 涡激共振　；参考：《湖南大学》2015年硕士论文

【摘要】：大跨度桥梁是现代交通系统的重要基础设施,世界正进入超大跨度桥梁建设的时代,而抗风性能是大跨度桥梁设计中关键问题之一。已有抗风设计方法已避免了灾难性的颤振失稳发生,但钢箱梁桥的涡激共振问题是困扰抗风研究的一个重要问题。进行主梁刚性节段缩尺模型的弹性悬挂动力试验是检验主梁涡振性能的常用手段。按风洞尺寸要求,节段模型的缩尺比在1/80~1/20左右。然而,已有的一些风洞试验结果表明,模型缩尺比的不同会造成无量纲振幅有显著差异。其作用机理尚不明确。本文在国家自然科学基金的资助下,以1:6矩形断面对研究对象,对涡激共振的模型尺度效应进行了试验研究,重点讨论模型长宽比对涡振振幅、表面脉动压力及其展向相关性的影响。本论文的主要工作如下:(1)介绍了颤振、驰振,抖振以及涡激振动的基本理论,重点并列举了世界上几个比较著名的桥梁涡激振动实例,同时简述了本文的研究背景和内容。(2)基于涡激振动的简谐力模型阐述了影响涡振振幅的主要参数,包括脉动升力系数、Strouhal数(St数)、反映阻尼和质量综合效应的Scruton数(Sc数)和涡激力的展向相关性。同时对气动外形、雷诺数、来流湍流等影响上述参数的因素进行了分析。(3)设计制作了宽高比为6的一个大尺度模型(B=72cm,H=12cm)和两个小尺度模型(B=40cm,H=6.7m)。大尺度模型长1.54m,相应的长宽比为2.14;小尺度模型长分别为1.54m和2.3m,相应的长宽比分别为3.85和5.75。进行了均匀流场中相同Sc数时的节段模型涡激共振测振试验。结果表明,三个试验模型均出现了两个明显的涡激振动区间,第二涡激振动区间的最大振幅大于第一涡激振动区间的最大振幅。且两个小尺度模型的最大无量纲振幅基本相同,大尺度模型最大无量纲振幅约只有两个小尺度模型的最大无量纲振幅的一半。(4)对三个模型表面压力系数均方差、升力系数均方差以及相同无量纲振幅下的升力展向相关性进行了研究,结果表明L/B=2.14的大尺度模型的表面压力系数均方差、升力系数均方差及升力展向相关性要明显小于两个小尺度模型(L/B=3.85,L/B=5.75)的表面压力系数均方差、升力系数均方差以及升力展向相关性,同时对振幅以及紊流对于展向相关性的影响也进行了研究。(5)利用CFD对小尺度短模型进行了二维数值模拟,并与试验结果进行对比,涡振锁定区间与试验结果基本吻合,第二涡激振动区间最大无量纲振幅略有差异。
[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.

【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.3

【参考文献】