Effects Of Leading-edge-vortex On The Vortex-induced-vibration Of Bluff Body

Long-span-bridges has improved the social development and the economic communication because of its ability to transport over rivers and valleys.However,large-amplitude-vibrations happens more frequently under wind effect because of lower stiffness and damping of the whole structure,which greatly influence the safety.Vortex-induced-vibration is one kind of large-amplitude-vibrations happened in long-span bridges we usually see.Great flow separation and vortex shedding happen at the leading edge of bridge girder because of the sharp edge of cross-section and accessory structures.Leading-edge-separation and leading-edge-vortex play important roles in wind-induced-vibration of bridge girder.To research this kind of forefront field in wind engineering of bridges,this paper research has researched the leading-edge-separation and leading-edge-vortex shedding of bridge girder cross-section.The concrete research contents are listed as follow:Firstly,we designed the aerodynamic configuration of the bridge girder mode,a vertical plate whose height is changeable was set in the leading edge in order to control the flow separation from the leading edge.Testing system was constructed to acquire wind velocity,pressure distribution and vibration information.Analysis of the characteristics of flow field of the static mode and dynamic mode are base on wind-tunnel-experiments.Secondly,we studied the separation flow from the leading edge,the leading edge structures and the vortex shedding frequency and their relations with the changing height of the leading-edge-plate.Characteristics of separating flow from the leading edge was also studied to find the wake effects on leading-edge-separation when there is a split plate in the wake of the model.Finally,we studied the vortex-induced-vibration of the bridge girder mode with leading-edge-plate.Analysis of the characteristics of vibration response,aerodynamic forces and vortex in the fluid-structure interaction was conducted to reveal the leading-edge-vortex effects on vortex-induced-vibration.