【摘要】：橋梁在人們的生活中隨處可見,斜拉橋是一種由橋跨結(jié)構(gòu)、橋梁支座系統(tǒng)、斜拉索等部件組成。在斜拉橋設(shè)計(jì)、施工和使用過程中,斜拉索已成為制約斜拉橋使用壽命的關(guān)鍵因素。風(fēng)一旦吹過斜拉索的表面,它的尾流后面會(huì)出現(xiàn)周期性的渦結(jié)構(gòu)脫落,這種周期性的漩渦結(jié)構(gòu)的脫落會(huì)使斜拉索表面呈現(xiàn)縱向和橫向的非定常載荷,嚴(yán)重時(shí)會(huì)激起振動(dòng)響應(yīng)。這種長期的誘導(dǎo)振動(dòng)會(huì)導(dǎo)致斜拉索的疲勞損壞,繼而發(fā)生災(zāi)難性事件,因此,對(duì)斜拉索渦致耦合振動(dòng)特性的研究具有十分重要的意義。課題組前期提出一種表面形狀沿展向呈余弦函數(shù)曲線變化的波浪型斜拉索,相比于傳統(tǒng)的斜拉索具有一定的減阻減振效果,本文主要針對(duì)高雷諾數(shù)下波浪型斜拉索渦激振動(dòng)進(jìn)行實(shí)驗(yàn)研究。前期對(duì)波浪型斜拉索高雷諾數(shù)下靜止繞流進(jìn)行了數(shù)值模擬計(jì)算,結(jié)果表明:當(dāng)4Re?1?10時(shí),波浪型斜拉索?/D?2和?/D?6均具有一定的減阻減振效果,其中?/D?2,a/D?0.3和?/D?6,a/D?0.15的阻力系數(shù)分別減小到了0.78和0.89,主要是由于波浪型斜拉索沿展向周期性變化,形成更穩(wěn)定的三維剪切層,它改變了拉索表面壓力分布,抑制了渦脫的形成,從而具有減阻減振特性;在小風(fēng)洞里采用三分量力傳感器和眼鏡蛇探針對(duì)它的升阻力系數(shù)以及速度相關(guān)性進(jìn)行實(shí)驗(yàn)分析,發(fā)現(xiàn)波浪型斜拉索?/D?2,a/D?0.15在4 5Re?1?10 1?10里,阻力系數(shù)均比直斜拉索小,當(dāng)4Re?1?10時(shí)最大減阻效果達(dá)到15.8%,同時(shí)它在4Re?4?10時(shí)脈動(dòng)升力系數(shù)相比于直斜拉索也有所減小;最后本文進(jìn)一步對(duì)波浪型斜拉索進(jìn)行渦激振動(dòng)實(shí)驗(yàn)研究,主要采用熱線風(fēng)速儀、激光位移傳感器和煙線等實(shí)驗(yàn)方法,研究了在Re=6800 20480區(qū)域內(nèi)波浪型狀斜拉索渦致耦合振動(dòng)及頻率“鎖定”現(xiàn)象,并引入直斜拉索作為對(duì)比。實(shí)驗(yàn)表明:在相同的質(zhì)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和直斜拉索同樣容易被誘導(dǎo)發(fā)生振動(dòng),波浪型?/D?2,a/D?0.15比波浪型?/D?6,a/D?0.075的減振效果要好,和直斜拉索相比,誘導(dǎo)振動(dòng)時(shí)最大振幅減小了10%,鎖定區(qū)間變短,主要是由于它的表面凹凸變化傾斜度較大,沿展向二次渦強(qiáng)度得以增強(qiáng),一旦誘導(dǎo)振動(dòng),將干擾斜拉索的漩渦激勵(lì),從而達(dá)到減振的目的。本文通過對(duì)波浪型斜拉索在高雷諾數(shù)下靜止繞流和渦激振動(dòng)的減阻減振研究,為波浪型斜拉索的實(shí)際應(yīng)用進(jìn)一步奠定了理論基礎(chǔ)。
[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.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U446;U448.27

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本文編號(hào)：2396883