桥塔尾流致塔周长吊索涡振性能研究

Vortex-induced vibration of long suspenders nearby the tower in the wake of bridge tower

  • 摘要: 悬索桥桥塔周围的长吊索自振频率较低,且易受桥塔尾流的干扰从而容易发生振动。吊索的安全直接关系着桥梁结构的安全,以实际工程为背景,采用CFD数值模拟方法并选择SST k-ω湍流模型对二维桥塔断面及吊索断面的非定常绕流进行了分析。首先,计算了桥塔和吊索各自的气动特性,并与相关文献的结果进行了对比。在验证分析方法可靠性的基础上,进一步研究了不同来流风速、风向角下,桥塔尾流对塔周长吊索气动特性的干扰。通过对流场特征及吊索气动力的变化规律进行分析,研究了桥塔尾流作用下塔周长吊索发生涡振的可能性。研究结果表明:在相当大的风向角范围内,桥塔脱落的旋涡会对吊索气动特性产生控制作用,从而导致吊索阻力系数和升力系数的变化频率等于桥塔的旋涡脱落频率,使吊索在低风速下存在发生涡激共振的可能性。

     

    Abstract: The long suspenders nearby the tower of suspension bridge are prone to produce vibration performance in the wake of bridge tower due to their low natural frequencies. The suspender safety is closely related to the structural safety of bridge. The CFD numerical simulation was adopted and the SST k-ω turbulence model was chosen to analyze the unsteady flow around a 2D bridge tower and a 2D suspender according to a practical suspension bridge. First, the respective aerodynamic characteristic of the bridge tower and the suspender was calculated and compared with the results of related literatures. The effects of the wake of bridge tower on the aerodynamic characteristics of long suspenders nearby the pylon were analyzed under the condition of various wind velocities and directions after checking the reliability of the analysis method. The possibility of vortex-induced vibration of long suspenders nearby the tower in the wake of bridge tower was researched by analyzing the flow field characteristics and the change of aerodynamic forces of suspenders. The results indicate that vortex shedding from bridge tower has a strong influence on aerodynamic characteristics of suspenders at a wide range of wind directions, which may lead to vortex-induced vibration of suspenders at low wind velocity because the frequencies of drag and lift coefficient of suspenders are close to the frequency of vortex shedding from bridge tower.

     

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