Numerical Simulation On Vibration Of Suspension Cables Induced By Wake Of Upstream Bridge Tower

Suspension bridges become preferred form of long-span bridge due to the long span、aesthetics、lightness and reasonable force. The longest suspension cable close to bridge tower has large slenderness ratio and low natural frequency. Winds separate obviously when blow across bridge tower, create large vortex street and large wake-affected zone. The effect of tower may cause vibration of downstream cables in large amplitude. Over time, flexible cables are easily destroyed due to large amplitude or collision. This article studies the response of wind-induced vibration by using the CFD methods based on finite volume method.Firstly, to verify the correctness of the CFD method using in this article conduct numerical computation on unsteady flow around a circular cylinder and vortex-induced vibration. Find out that eigenvalues of aerodynamic force are in good agreement with experiment results in small Reynolds number, however, slightly larger than experiment results in large Reynolds number. This is due to weak correlation of moving interface in small Reynolds number, but actual flows present three-dimensional character in large Reynolds number. Besides, the displacement amplitude of simulation on VIV of a singular cylinder at different reduced velocity when ? = 0.0208 and = 100 are in good agreement with previous literature in same working condition as well.Secondly, conduct numerical computation on flow around four circular cylinders in rectangular configuration and free vibration of the cylinders in two directions, find out that when =45°, the displacement amplitude of four cylinders in cross-flow direction all reach the maximum, the displacement amplitude of cylinder2 and cylinder4 in along-wind direction also reach the maximum, besides, the displacement amplitude of cylinder4 increase greatly compares to the results of a singular cylinder, therefore, we consider the interaction between four cylinders when =45° as the most disadvantage situation.Finally, conduct numerical computation on flow around suspenders influenced by the wake of bridge tower and the vibration of suspenders in two directions. For flow around suspenders, we find that the aerodynamic force of suspenders decrease obviously compares with result of flow around a singular cylinder, the primary frequency of suspenders are the same with vortex shedding frequency of bridge tower. As the wind angel increases, change of lift force of suspenders in back row begin to be controlled by the wake of bridge tower as well as the vortex shedding of itself. For flow-induced vibration, we find that the large amplitude vibration of suspenders are due to approximation of natural frequency and the vortex shedding frequency of bridge tower, motivated by the wake of bridge tower, suspenders vibrate in large amplitude along an elliptical orbit sim ilar to the phenomenon of resonance.