波浪型斜拉索横向与流向受迫振动的数值研究
发布时间：2018-09-09 16:44
【摘要】：斜拉桥是一种由桥塔、主梁、斜拉索三种基本构件组成的组合结构，由于其具有良好的力学性能、相对低廉的造价及精致的外观，近年来已成为大跨径桥梁建设中最有竞争力的桥型。斜拉索作为主要承重构件之一，当有风从其一侧吹过，尾流中会出现周期性的涡脱落，这种周期性的涡脱落会诱发作用在斜拉索上的纵向和横向的非定常载荷，进而激起振动响应。长期的振动会引起构件疲劳，甚至导致桥梁完全损坏继而发生灾难性事件，因此，探明斜拉索涡激耦合振动特性具有十分重要的意义。 本文在课题组前期研究基础上发现：某些特定波浪形状的斜拉索由于其上下表面沿展向方向呈正弦曲线变化，延缓了自由剪切层的分离，抑制了卡门涡街的产生，减阻可高达18%且脉动升力系数趋近于0。基于此，本文以新型波浪型圆柱为研究对象，在N-S方程的基础上，对雷诺数Re=100下特定波浪形状(λ*=2和λ*=6)两种波浪型圆柱在均匀来流中横向与流向受迫振动展开系统的数值研究，得到了升阻力系数随振动频率的变化关系以及在不同振幅下的锁定区间和尾流结构2P,2S,P+S三种典型涡脱形态。 研究结果表明：横向受迫振动时，对于λ*=2波浪型圆柱，减阻效果不明显，阻力系数只在锁定区前较直圆柱略小，但具有较好减振效果；λ*=6波浪型圆柱则表现出更为良好的减阻减振效果，在振幅比A*=0.2和0.4条件下最大减阻分别可达20%和30%，减振高达93%和78%，尾流结构发现2S、2P等涡脱形式。流向受迫振动时，λ*=2波浪型圆柱仅在振幅比A*=0.1时有减振效果，λ*=6波浪型圆柱则在振幅比A*=0.1和0.3条件下仍然保持良好的减阻减振效果，这说明在小振幅比下，λ*=6波浪型圆柱在横向与流向受迫振动中均保持良好的减阻减振效果，表现出良好的气动性能，，在圆柱尾流发现了A-I、A-III和A-IV模态，并观察到不同模态之间的竞争与转化。 本文通过对波浪型斜拉索横向与流向受迫振动的数值研究，为波浪型斜拉索振动特性的进一步研究奠定了重要基础。
[Abstract]:The cable-stayed bridge is a kind of composite structure composed of three basic components: the bridge tower, the main beam and the stay cable. Because of its good mechanical properties, relatively low cost and exquisite appearance, the cable-stayed bridge is composed of three basic components: the bridge tower, the main beam and the cable-stayed cable. In recent years, it has become the most competitive bridge in the construction of long-span bridges. As one of the main load-bearing elements, the periodic vortex shedding will occur in the wake when wind blows over the cable, which will induce the longitudinal and lateral unsteady loads acting on the stay cable. And then stimulate the vibration response. Long term vibration will cause fatigue of members and even lead to complete damage of bridges and then catastrophic events. Therefore, it is of great significance to study the characteristics of vortex-induced coupled vibration of stay cables. On the basis of the previous research by the research group, it is found that some cable-stayed cables with certain wave-shaped shapes exhibit sinusoidal changes in the upper and lower surface along the spanwise direction, which delays the separation of the free shear layer and inhibits the production of Carmen vortex street. Drag reduction can be as high as 18% and the pulsating lift coefficient approaches 0. In this paper, a new type of wave-shaped cylinder is studied. On the basis of N-S equation, a numerical study of the forced lateral and directional vibration of two kinds of wave-shaped cylinders under Reynolds number Re=100 (位 ~ (2) and 位 ~ (6) in a uniform flow is carried out. The variation of the lift resistance coefficient with the vibration frequency and the three typical vortex demoralization patterns of the wake structure 2Pn2SnP S and the lock-in interval at different amplitudes are obtained. The results show that the drag reduction effect is not obvious and the drag coefficient is only a little smaller than that of the straight cylinder before locking area, but it has a better damping effect. The maximum drag reduction of the wave type cylinder is 20% and 30% respectively under the condition of amplitude ratio of 0.2 and 0.4, and the damping is 93% and 78%, respectively. The wake structure has a 2Sn2P isosortex debridement form, and the maximum drag reduction is 20% and 30%, respectively, when the amplitude ratio is 0. 2 and 0. 4, respectively, and the vibration reduction is 93% and 78%, respectively. When the flow direction is forced to vibrate, the wave type cylinder only has the effect of reducing vibration when the amplitude ratio is 0.1, while the wave type cylinder of the lambda 6 can still keep the good effect of drag damping at the condition of amplitude ratio of 0.1 and 0.3. The results show that the lambda 6 wave-type cylinder has good drag damping and damping effect in both transverse and directional forced vibration under small amplitude ratio, and shows good aerodynamic performance. A-IZO A-III and A-IV modes have been found in the wake of the cylinder, and the results are as follows: (1) in the wake of the cylinder, the A-IZO A-III and A-IV modes are found. The competition and transformation between different modes were observed. In this paper, the numerical study on the forced vibration of wave-type cables is carried out, which lays an important foundation for the further study of the vibration characteristics of wavy 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】：2014
【分类号】：U441.3;U448.27
本文编号：2232989
[Abstract]:The cable-stayed bridge is a kind of composite structure composed of three basic components: the bridge tower, the main beam and the stay cable. Because of its good mechanical properties, relatively low cost and exquisite appearance, the cable-stayed bridge is composed of three basic components: the bridge tower, the main beam and the cable-stayed cable. In recent years, it has become the most competitive bridge in the construction of long-span bridges. As one of the main load-bearing elements, the periodic vortex shedding will occur in the wake when wind blows over the cable, which will induce the longitudinal and lateral unsteady loads acting on the stay cable. And then stimulate the vibration response. Long term vibration will cause fatigue of members and even lead to complete damage of bridges and then catastrophic events. Therefore, it is of great significance to study the characteristics of vortex-induced coupled vibration of stay cables. On the basis of the previous research by the research group, it is found that some cable-stayed cables with certain wave-shaped shapes exhibit sinusoidal changes in the upper and lower surface along the spanwise direction, which delays the separation of the free shear layer and inhibits the production of Carmen vortex street. Drag reduction can be as high as 18% and the pulsating lift coefficient approaches 0. In this paper, a new type of wave-shaped cylinder is studied. On the basis of N-S equation, a numerical study of the forced lateral and directional vibration of two kinds of wave-shaped cylinders under Reynolds number Re=100 (位 ~ (2) and 位 ~ (6) in a uniform flow is carried out. The variation of the lift resistance coefficient with the vibration frequency and the three typical vortex demoralization patterns of the wake structure 2Pn2SnP S and the lock-in interval at different amplitudes are obtained. The results show that the drag reduction effect is not obvious and the drag coefficient is only a little smaller than that of the straight cylinder before locking area, but it has a better damping effect. The maximum drag reduction of the wave type cylinder is 20% and 30% respectively under the condition of amplitude ratio of 0.2 and 0.4, and the damping is 93% and 78%, respectively. The wake structure has a 2Sn2P isosortex debridement form, and the maximum drag reduction is 20% and 30%, respectively, when the amplitude ratio is 0. 2 and 0. 4, respectively, and the vibration reduction is 93% and 78%, respectively. When the flow direction is forced to vibrate, the wave type cylinder only has the effect of reducing vibration when the amplitude ratio is 0.1, while the wave type cylinder of the lambda 6 can still keep the good effect of drag damping at the condition of amplitude ratio of 0.1 and 0.3. The results show that the lambda 6 wave-type cylinder has good drag damping and damping effect in both transverse and directional forced vibration under small amplitude ratio, and shows good aerodynamic performance. A-IZO A-III and A-IV modes have been found in the wake of the cylinder, and the results are as follows: (1) in the wake of the cylinder, the A-IZO A-III and A-IV modes are found. The competition and transformation between different modes were observed. In this paper, the numerical study on the forced vibration of wave-type cables is carried out, which lays an important foundation for the further study of the vibration characteristics of wavy 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】：2014
【分类号】：U441.3;U448.27
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