拱桥吊杆气动性能的二维数值模拟

发布时间：2018-03-05 06:29

本文选题：风荷载　切入点：FLUENT　出处：《郑州大学》2014年硕士论文　论文类型：学位论文

【摘要】：风荷载会对桥梁结构的安全性和稳定性造成重要的影响。涡激振动是一种常见的风致振动现象，非常容易出现在阻尼小且细长的结构上，可能会引起结构的疲劳损伤，并对交通安全造成一定的影响。目前结构的发展方向是长、细、柔和弱阻尼，因此需要研究结构的涡激振动问题。南京大胜关长江大桥吊杆的长度超过了50m，柔度很大，出现涡激振动的可能性非常大。本文的主要工作是利用大型流体计算力学软件FLUENT对该桥吊杆的气动性能进行数值模拟，从而为涡激振动的研究提供基础。通过对升力系数、阻力系数和旋涡脱落图的对比分析，，从长方形、切角长方形和圆角长方形这三种参考截面中选择出气动性能最优的吊杆截面，从而达到减小风致振动影响的目的。结合以上所做的工作并考虑实际工程情况，对单根和双根切角长方形截面吊杆的气动性能分别进行数值模拟，并将两种情况下得到结果进行对比分析，找出最不利风攻角的范围和两根杆件脱离相互干扰时的风攻角值。本文通过以上工作得到以下结论： (1)随着风速的不断增加，各截面吊杆所对应的斯特罗哈数近似为一常数。 (2)随着风速的不断增加，各截面吊杆的升力和阻力也是不断增大的。 (3)从长方形截面到切角长方形截面再到圆角长方形截面，发生涡激振动时的起振风速是在不断减小的。 (4)在同一风速情况下，从长方形截面到切角长方形截面再到圆角长方形截面，升力系数、升力、阻力系数、阻力是不断减小的。 (5)在有风攻角情况下对单根切角长方形截面杆件的气动性能进行数值模拟，得到其最不利风攻角出现在20°~25°之间。 (6)对双根切角长方形截面杆件的气动性能进行数值模拟，并考虑风攻角变化的影响，得到双根杆件脱离相互干扰的风攻角值大致为15°。
[Abstract]:Vortex-induced vibration is a common wind-induced vibration phenomenon, which is very easy to appear on the structure with small damping and slender length, which may cause fatigue damage of the bridge structure. At present, the development direction of the structure is long, fine, soft and weak damping, so it is necessary to study the vortex-induced vibration of the structure. The length of suspension rod of Nanjing Dashengguan Yangtze River Bridge is more than 50 m, the flexibility is very large, and the possibility of vortex-induced vibration is very high. The main work of this paper is to simulate the aerodynamic performance of suspension rod of the bridge by using the large-scale fluid computational mechanics software FLUENT. Through the comparative analysis of lift coefficient, drag coefficient and vortex shedding diagram, from the rectangle, In order to reduce the effect of wind-induced vibration, the optimal aerodynamic performance of suspender section is selected among the three reference cross-sections of tangent rectangle and circular rectangle. Combined with the above work and considering the actual engineering situation, the aerodynamic performance of single and double tangential rectangular section suspenders are numerically simulated, and the results obtained under the two conditions are compared and analyzed. Find out the range of the most unfavorable wind angle of attack and the wind angle of attack when the two bars are separated from each other. In this paper, the following conclusions are obtained from the above work:. 1) with the increasing of wind speed, the Sloan number corresponding to each section of the suspender is approximately a constant. 2) with the increasing of wind speed, the lifting force and resistance of each section of suspender are also increasing. (3) from rectangular section to tangent rectangle section to rounded rectangular section, the wind speed of starting vibration is decreasing when vortex-induced vibration occurs. 4) under the same wind speed, the lift coefficient, lift coefficient, resistance coefficient and resistance coefficient are decreasing continuously from rectangular section to tangent rectangle section to rounded rectangular section. 5) the aerodynamic performance of rectangular cross-section members with single tangent angle is numerically simulated under the condition of wind attack angle, and the most unfavorable wind attack angle appears between 20 掳and 25 掳. The aerodynamic performance of rectangular cross-section bar with double tangent angle is numerically simulated. Considering the influence of wind attack angle, the wind attack angle of double bar is about 15 掳.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.3;U448.22

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