超临界雷诺数下拉索顺风向自激力特性研究

Characteristics of along-wind self-excited forces of a cable under super-critical Reynolds number

为获得超临界雷诺数下拉索顺风向振动自激力特性,推导了拉索与顺风向阻尼相关的颤振导数准定常解析值。为保证数值模拟的质量,基于固定拉索CFD计算的网格无关性检查,确定了振动拉索数值模拟的合理参数和气动力系数。开展了雷诺数为5.18×105,折算风速在53~1 050范围内拉索顺风向强迫振动数值模拟和拉索颤振导数P*1识别,研究结果与准定常解析值的良好一致性,说明了方法的合理性,研究表明能采用准定常解析值来确定拉索超高折算风速下的颤振导数P*1。研究同时表明,在超高折算风速和拉索顺风向振动情况下,拉索涡脱力显著主导气动力,拉索振动不改变拉索的漩涡脱落频率,因此拉索自激气动力可忽略,风荷载只需考虑涡脱力。

In order to evaluate the along-wind self-excited forces of cables under super-critical Reynolds number,the flutter derivative relavant to the along-wind damping of the cable is derived according to the quasi-steady theory.To ensure the validity of CFD simulation,suitable parameters and aerodynamic coefficients are determined based on the grid independency check for a fixed cable.In order to indentify the flutter derivatives of P*1,the flow fields around the along-wind forced vibrating cable are simulated with the reduced wind speeds ranged from 53~1050and Reynolds number of 5.18×105.The presented results are in good agreement with thoese from the quasi-steady theory,which shows the validity of the present method.It indicates that the flutter derivative of P*1under extreme wind speeds can be determined through the quasi-steady theory.It also indicates that under the condition of super high wind speed in along-wind condition,the vortex-shedding forces will dominate the total aerodynamic forces and the self-excitation vibration does not change the inherent vortex shedding frequency.It suggests that the selfexcited forces on cables are negligible under super high wind speed in along-wind action,and only vortex-shedding forces need to be considered.