The Analysis Of The Flow Of The Cylinder And The Wake Of A Cable-stayed Bridge

Cable-stayed bridge is widely used in modern bridge construction because of its large span and beautiful shape.But because of the big flexibility,light weight and low damping of the cable,vibration response happens easily under the influence of vehicle load,wind load and so on,threatening bridge safety.With the increase of the span of cable-stayed bridge,the windinduced vibration has increasingly attracted the attention of bridge workers and has become a hot research topic.The wind-induced vibration problem is essentially a circular flow problem.In this paper,CFD numerical simulation method is used to study the flow characteristics of the single cylinder and double cylinder of a cable diameter cylinder with low wind speed and high wind speed,and the analysis of the tail current of the longest cable in a cable-stayed bridge in the design is carried out.The design proposal is given.The main contents are as follows:1.This paper summarizes the research results and research methods of the wind vibration phenomena,such as cylinder winding and wake,and expounds the research methods and research ideas of this paper.2.Through the ANSYS Fluent software,a two-dimensional flow field model is used to simulate the flow around a single cylinder with a cable diameter cylinder with low wind speed and high wind velocity.The flow characteristics of the single cylinder flow under the low wind speed and small Reynolds number flow are expounded.The change relationship of the starting parameters of the cable and the Reynolds number of the fluid are analyzed.3.Taking the cable diameter of a cable-stayed bridge in the design as the object,the flow characteristics of the parallel and tandem flow around a double cylinder under low wind speed and small Reynolds number flow are studied.The critical distance between the two columns and the parallel flow is obtained.Before the critical distance,the vortex shedding does not occur in the upstream cylinder before the critical distance,and the vortex shedding will occur at the critical distance after the critical spacing.The drag coefficient is raised at the critical distance,and the number of strouhal can produce a sudden increase of the "step type",and there is also a critical distance between the flow around the flow and a critical distance.The critical distance flow will have a "double wake drift phenomenon,is greater than the critical spacing,independent and symmetric reverse flow.4.Based on the cable diameter of a cable-stayed bridge in the design,the flow characteristics of parallel and tandem flow around a double cylinder under high wind speed and large Reynolds number turbulence are carried out.On the basis of this study,the large eddy simulation is carried out in the middle cable of the cable-stayed bridge.The wake of the downstream cable is determined by the Den Hartog criterion.The wind speed of the cable is 3.767m/s.Therefore,it is suggested that the damper should be set up to increase the damping ratio of the cable to increase the wind speed and reduce the probability of the tail current.In addition,the connecting rod can be set up between the cables to improve the wind speed,which is of certain guiding significance to the design of the bridge.