斜腹板倾角对桥梁气动稳定性影响的数值模拟研究
发布时间：2018-09-08 10:10
【摘要】：自从1966年流线型箱梁被应用于英国的赛文桥以来,它就以较高的扭转刚度、优越的气动力特性和经济性而被桥梁设计者们广泛采用。我国近几十年来建造的大部分大跨度桥梁主梁都采用了流线型箱梁的形式。与传统的大跨度桁架桥梁类似,颤振稳定性仍是设计中要考虑的重要问题,而另一个挑战就是涡激振动,这也是箱梁断面的固有特性之一。从空气动力学的角度看,流线型箱梁截面仍属于钝体,会导致气流分离。箱梁的斜腹板的倾角越小,越趋近于平板,气动力特性就越好。然而过小的倾角会导致其他的问题,如一些附属构件和设备的安装。对南京四桥和其他一些大跨度流线型箱梁桥的风洞试验表明,颤振临界风速会在斜腹板倾角小于16。时明显提高。本文以南京四桥为工程背景,以1：20的几何缩尺比构建计算模型。用数值模拟的方法研究了桥梁截面斜腹板倾角对气动稳定性的影响及其抑制涡激振动的机理。共研究了16种不同的倾角,分别为：12。-21。、23。、25。、35。、45。、75。和90。。本文研究的主要内容有：(1)用二维N-S方程和SST k-ω湍流模型,采用定常算法进行三分力计算,研究不同倾角对三分力的影响。研究结果表明,倾角的改变对阻力和升力系数影响较大,而对扭矩系数影响不明显。且倾角越小,气动力特性越好。(2)用强迫振动法对颤振性能进行模拟计算,假设结构分别做纯竖向和纯扭转振动并记录升力和扭矩时程曲线,然后用最小二乘法拟合得到8个颤振导数。结果显示：当斜腹板倾角为17。时,颤振导数H1*和A2*出现最小值。颤振稳定性在倾角为17。时会大大提高。(3)用二维大涡模拟的方法进行涡激振动的分析,通过UDF编程实现结构与流体的耦合。结果表明：当斜腹板倾角小于17。时,会抑制斜腹板后方大尺度漩涡的产生,从而有效减小涡激共振的可能性。
[Abstract]:Since the streamline box girder was applied to the Severn Bridge in England in 1966, it has been widely used by bridge designers because of its high torsional stiffness, superior aerodynamic characteristics and economy. In recent decades, most of the long-span bridge main beams are streamlined box girder. Similar to the traditional long-span truss bridge, flutter stability is still an important issue to be considered in the design, and another challenge is vortex-induced vibration, which is also one of the inherent characteristics of box girder section. From the viewpoint of aerodynamics, the section of streamlined box girder is still a blunt body, which will lead to the separation of air flow. The smaller the inclined angle of the box girder, the closer to the flat plate, the better the aerodynamic characteristics. However, too small inclination can lead to other problems, such as the installation of accessories and equipment. Wind tunnel tests of Nanjing fourth Bridge and other large span streamlined box girder bridges show that the critical flutter velocity is less than 16. Time is obviously improved. In this paper, the fourth Nanjing Bridge is used as the engineering background, and the calculation model is constructed with the geometric scale ratio of 1:20. The effect of inclined angle on aerodynamic stability and the mechanism of suppressing vortex-induced vibration are studied by means of numerical simulation. A total of 16 different inclination angles were studied, which are respectively: 1. 12. -21. 1. 23. 25. 5. 5. 5. 75. And 90. The main contents of this paper are as follows: (1) by using two-dimensional N-S equation and SST k- 蠅 turbulence model, a steady algorithm is used to calculate the three-point force, and the influence of different inclination angles on the three-point force is studied. The results show that the change of inclination angle has great influence on resistance and lift coefficient, but not on torque coefficient. And the smaller the inclination angle, the better the aerodynamic characteristics. (2) the flutter performance is simulated by forced vibration method, assuming the pure vertical and torsional vibration of the structure are made and the lift and torque time history curves are recorded, respectively. Then eight flutter derivatives are obtained by least square fitting. The results showed that the inclination angle of the oblique web was 17.7%. The flutter derivatives H 1 * and A 2 * are minimized. The flutter stability is 17. (3) the method of two-dimensional large eddy simulation is used to analyze the vortex-induced vibration, and the coupling between structure and fluid is realized by UDF programming. The results show that when the inclined web inclination is less than 17. The large scale vortex behind the oblique web can be inhibited and the possibility of VSR can be effectively reduced.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.3
本文编号：2230211
[Abstract]:Since the streamline box girder was applied to the Severn Bridge in England in 1966, it has been widely used by bridge designers because of its high torsional stiffness, superior aerodynamic characteristics and economy. In recent decades, most of the long-span bridge main beams are streamlined box girder. Similar to the traditional long-span truss bridge, flutter stability is still an important issue to be considered in the design, and another challenge is vortex-induced vibration, which is also one of the inherent characteristics of box girder section. From the viewpoint of aerodynamics, the section of streamlined box girder is still a blunt body, which will lead to the separation of air flow. The smaller the inclined angle of the box girder, the closer to the flat plate, the better the aerodynamic characteristics. However, too small inclination can lead to other problems, such as the installation of accessories and equipment. Wind tunnel tests of Nanjing fourth Bridge and other large span streamlined box girder bridges show that the critical flutter velocity is less than 16. Time is obviously improved. In this paper, the fourth Nanjing Bridge is used as the engineering background, and the calculation model is constructed with the geometric scale ratio of 1:20. The effect of inclined angle on aerodynamic stability and the mechanism of suppressing vortex-induced vibration are studied by means of numerical simulation. A total of 16 different inclination angles were studied, which are respectively: 1. 12. -21. 1. 23. 25. 5. 5. 5. 75. And 90. The main contents of this paper are as follows: (1) by using two-dimensional N-S equation and SST k- 蠅 turbulence model, a steady algorithm is used to calculate the three-point force, and the influence of different inclination angles on the three-point force is studied. The results show that the change of inclination angle has great influence on resistance and lift coefficient, but not on torque coefficient. And the smaller the inclination angle, the better the aerodynamic characteristics. (2) the flutter performance is simulated by forced vibration method, assuming the pure vertical and torsional vibration of the structure are made and the lift and torque time history curves are recorded, respectively. Then eight flutter derivatives are obtained by least square fitting. The results showed that the inclination angle of the oblique web was 17.7%. The flutter derivatives H 1 * and A 2 * are minimized. The flutter stability is 17. (3) the method of two-dimensional large eddy simulation is used to analyze the vortex-induced vibration, and the coupling between structure and fluid is realized by UDF programming. The results show that when the inclined web inclination is less than 17. The large scale vortex behind the oblique web can be inhibited and the possibility of VSR can be effectively reduced.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.3
【参考文献】
相关期刊论文 前1条
1 周志勇,陈艾荣,项海帆;涡方法分析并列圆柱的旋涡脱落现象[J];空气动力学学报;2003年01期
，本文编号：2230211
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