本文選題：懸索橋 + 吊桿�。� 參考：《哈爾濱工業(yè)大學》2015年碩士論文

【摘要】：懸索橋由于其跨徑大,美觀輕盈,受力合理而成為大跨度橋梁的首選形式。但靠近橋塔的吊桿長細比很大,自振頻率低,風吹過橋塔時沿順風向發(fā)生較大分離,并在尾流形成較大尾流渦街,其尾流場影響區(qū)大,下游吊桿可能在這種尾流影響下發(fā)生振幅很大的馳振。長此以往,柔性吊桿很容易因振幅過大或相互之間的碰撞而發(fā)生破壞。本文通過基于有限體積法的計算流體力學方法,對吊桿在尾流影響下發(fā)生風致振動的響應進行研究。首先為了驗證本文所用數(shù)值方法的可靠性,對單圓柱的固定繞流和流致振動進行了二維模擬。發(fā)現(xiàn)雷諾數(shù)較小時得到的氣動力特征值與試驗結果吻合很好,雷諾數(shù)較大時,本文得到的氣動力結果比試驗略大。這是因為雷諾數(shù)較小時流動界面的相關性小,雷諾數(shù)較大時,實際流動呈現(xiàn)三維特性,而二維模擬比較規(guī)則。對單圓柱的渦致振動在?=0.0208,=100時不同折減風速下進行了模擬,將得到的位移幅值與相同工況下前人的結果進行了比較,結果基本吻合。其次,對長方形排列四圓柱在沒有橋塔尾流影響下的固定繞流和流致振動進行了模擬,發(fā)現(xiàn)在=45°時,四圓柱的橫風向位移最大幅值均達到最大值,柱2和柱4的順風向位移最大幅值也達到了最大值,并且柱4兩方向位移最大幅值與單圓柱振動結果相比均有大幅增加,因此認為此時四圓柱間的相互氣動影響最為不利。最后,對吊桿在橋塔尾流影響下的固定繞流和流致振動進行了模擬,對于固定繞流,發(fā)現(xiàn)零風向角下吊桿的氣動力與單圓柱繞流結果相比有明顯減小,此時吊桿升力變化的一階頻率與橋塔漩渦脫落頻率完全相同,當來流風向角增大時,后排吊桿出現(xiàn)了升力變化開始由橋塔尾流和自身漩渦脫落共同控制的現(xiàn)象。對于流致振動,發(fā)現(xiàn)吊桿的大幅振蕩是由于其自振頻率與橋塔漩渦脫落頻率相近時,在橋塔尾流的激勵下,產生了類似于共振現(xiàn)象的沿橢圓形軌道的大幅振動。
[Abstract]:The suspension bridge has become the first choice of long-span bridges because of its large span, beautiful and lightness and reasonable force. However, the length of the suspension pole near the bridge tower is very large, the frequency of its self vibration is low, the wind blowing across the bridge tower is more separated along the wind direction, and the tail flow forms a large wake vortex street, and the tail flow field has a large influence area, and the downstream hanger may be affected by the wake. In the long run, the flexible hangers are easily damaged by excessive amplitude or collision between each other. In this paper, the response of the hanger to wind induced vibration is studied by the computational fluid mechanics method based on the finite volume method. First, the reliability of the numerical method used in this paper is verified. It is found that the aerodynamic characteristics of the Reynolds number are in good agreement with the experimental results. When the Reynolds number is large, the aerodynamic results are slightly larger than those of the test. This is because the correlation of the Reynolds number is smaller than the hourly flow interface, and the actual flow is larger when the Reynolds number is larger. The vortex induced vibration of a single cylinder is simulated under the different wind speed at =0.0208 and =100. The amplitude of the displacement is compared with the previous results under the same working condition, and the results are basically consistent. Secondly, the four cylinders in the rectangular arrangement are fixed under the influence of the tail flow without the bridge tower. The flow around and flow induced vibration are simulated. It is found that the maximum amplitude of the horizontal displacement of the four cylinders at =45 degrees reaches the maximum. The maximum amplitude of the displacement of the column 2 and the column 4 is also the maximum, and the maximum amplitude of the column 4 and two direction has a significant increase compared with the single cylinder vibration. Therefore, it is considered that the phase between the four cylinders is at this time. The mutual aerodynamic influence is most unfavorable. Finally, the fixed flow and flow induced vibration of the suspenders under the influence of the tail flow of the bridge tower are simulated. For the fixed flow, the aerodynamic force of the hanger is obviously reduced compared with the result of the single cylinder, and the first frequency of the lift change is exactly the same as the vortex shedding frequency of the bridge tower. When the wind direction angle increases, the lift force of the rear hanger appears to be controlled by the tail flow of the bridge tower and the vortex shedding of its own. For the flow induced vibration, it is found that the large oscillation of the hanger is due to the close frequency of its self vibration frequency to the vortex shedding frequency of the bridge tower, and the resonance phenomenon along the ellipsoid is produced under the excitation of the bridge tower tail flow. The large vibration of a circular orbit.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U441.3;U448.25

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本文編號：2036948