波浪型斜拉索涡激振动实验研究

发布时间：2018-12-31 17:23

【摘要】：桥梁在人们的生活中随处可见,斜拉桥是一种由桥跨结构、桥梁支座系统、斜拉索等部件组成。在斜拉桥设计、施工和使用过程中,斜拉索已成为制约斜拉桥使用寿命的关键因素。风一旦吹过斜拉索的表面,它的尾流后面会出现周期性的涡结构脱落,这种周期性的漩涡结构的脱落会使斜拉索表面呈现纵向和横向的非定常载荷,严重时会激起振动响应。这种长期的诱导振动会导致斜拉索的疲劳损坏,继而发生灾难性事件,因此,对斜拉索涡致耦合振动特性的研究具有十分重要的意义。课题组前期提出一种表面形状沿展向呈余弦函数曲线变化的波浪型斜拉索,相比于传统的斜拉索具有一定的减阻减振效果,本文主要针对高雷诺数下波浪型斜拉索涡激振动进行实验研究。前期对波浪型斜拉索高雷诺数下静止绕流进行了数值模拟计算,结果表明:当4Re?1?10时,波浪型斜拉索?/D?2和?/D?6均具有一定的减阻减振效果,其中?/D?2,a/D?0.3和?/D?6,a/D?0.15的阻力系数分别减小到了0.78和0.89,主要是由于波浪型斜拉索沿展向周期性变化,形成更稳定的三维剪切层,它改变了拉索表面压力分布,抑制了涡脱的形成,从而具有减阻减振特性;在小风洞里采用三分量力传感器和眼镜蛇探针对它的升阻力系数以及速度相关性进行实验分析,发现波浪型斜拉索?/D?2,a/D?0.15在4 5Re?1?10 1?10里,阻力系数均比直斜拉索小,当4Re?1?10时最大减阻效果达到15.8%,同时它在4Re?4?10时脉动升力系数相比于直斜拉索也有所减小;最后本文进一步对波浪型斜拉索进行涡激振动实验研究,主要采用热线风速仪、激光位移传感器和烟线等实验方法,研究了在Re=6800 20480区域内波浪型状斜拉索涡致耦合振动及频率“锁定”现象,并引入直斜拉索作为对比。实验表明:在相同的质量比和阻尼比下,波浪型斜拉索?/D?2,a/D?0.15、?/D?6,a/D?0.075和直斜拉索同样容易被诱导发生振动,波浪型?/D?2,a/D?0.15比波浪型?/D?6,a/D?0.075的减振效果要好,和直斜拉索相比,诱导振动时最大振幅减小了10%,锁定区间变短,主要是由于它的表面凹凸变化倾斜度较大,沿展向二次涡强度得以增强,一旦诱导振动,将干扰斜拉索的漩涡激励,从而达到减振的目的。本文通过对波浪型斜拉索在高雷诺数下静止绕流和涡激振动的减阻减振研究,为波浪型斜拉索的实际应用进一步奠定了理论基础。
[Abstract]:Bridges can be seen everywhere in people's lives. Cable-stayed bridges are composed of bridge span structure, bridge support system, cable-stayed cable and so on. In the process of design, construction and use of cable-stayed bridge, cable has become a key factor restricting the service life of cable-stayed bridge. Once the wind blows over the surface of the stay cable, there will be periodic vortex structure shedding behind its wake. This kind of periodic vortex structure shedding will make the cable surface appear longitudinal and transverse unsteady load, and will arouse vibration response when serious. This kind of long term induced vibration will lead to the fatigue damage of stay cables, and then catastrophic events will occur. Therefore, it is of great significance to study the characteristics of vortex-induced coupled vibration of stay cables. A wave-type stay cable whose surface shape changes along the curve of cosine function is proposed in the previous study. Compared with the traditional cable-stayed cable, it has a certain effect of reducing drag and damping vibration. In this paper, the vortex-induced vibration of wavy stay cables at high Reynolds number is studied experimentally. The numerical simulation of the static flow around the wave stayed cable at high Reynolds number has been carried out in the early stage. The results show that the wave type stay cable? / DU 2 and? / DU 6 have a certain effect of reducing drag and vibration when 4Ren 1? 10:00. Among them, the drag coefficients of? / D _ 2a / D _ (0.3) and? / D _ (6) / D _ (0. 15) decreased to 0.78 and 0.89, respectively, mainly due to the periodic variation of the wavy stay cables along the extension direction. A more stable three-dimensional shear layer is formed, which changes the pressure distribution on the surface of the cable and inhibits the formation of vortex detachment, thus having the characteristic of reducing drag and damping vibration. In a small wind tunnel, a three-component force sensor and a cobra probe were used to analyze the correlation between the lift resistance coefficient and the velocity. It was found that the wave-type stay cable? / D _ 2 / D _ (2) / D _ (0. 15) was within 4 5Re?1?10 / 10 miles. The drag coefficient is smaller than that of the straight stay cable, and the maximum drag reduction effect reaches 15.8 when 4Ren 1? 10:00, and the lift coefficient of pulsation at 4Ren 410:00 is also smaller than that of the straight stay cable. Finally, the vortex-induced vibration of wavy stay cables is studied by using hot wire anemometer, laser displacement sensor and smoke line. The vortex-induced coupled vibration of wavy stay cables and the phenomenon of frequency "locking" in the Re=6800 20480 region are studied, and the direct stay cables are introduced as a comparison. The experimental results show that under the same mass ratio and damping ratio, the wave-type stay cable? / D ~ (2) / D ~ (1) / D ~ (6) A / D _ (0.075) is easily induced to vibrate with the straight stay cable, and the wave type? / D ~ (2), The effect of a/D?0.15 is better than that of wave type? / D0. 075. Compared with the cable, the maximum amplitude of induced vibration is reduced by 10%, and the locking interval is shortened. It is mainly due to the large inclination of the surface concave and convex, the strength of the secondary vortex along the spanwise direction can be enhanced, once induced vibration, it will interfere with the vortex excitation of the stay cable, so as to achieve the purpose of vibration reduction. In this paper, the study of drag and vibration reduction of wave-type stay cables at high Reynolds number by static flow and vortex-induced vibration has laid a theoretical foundation for the practical application of wave-type stay cables.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446;U448.27

【参考文献】