Influence Of Floater Buoy On The Vortex Shedding Of Cylinder

Because of the advantages of high efficiency,simple design and flexible layout,the oscillating floater buoy wave energy device can be used in combination with other functional types of marine structures,so it has a high application prospect.It has made some progress in the study of the hydrodynamic characteristics of this structure,but most of the studies focus on the energy conversion efficiency.Very seldom studies focus on the influence on the loads and flow field of the original structure.While we have a good design concept of a marine structure,it also needs to consider the influence of various loads,This is closely related to the life of the structure and the mooring system.Based on this consideration,this thesis explores the influence on the loads and turbulence flow of the system when joining the floater.Based on OpenFOAM's large time step solver pimpleFoam,the numerical simulation of three-dimensional flow around a circular cylinder was verificated.Then,added the floater to the cylinder,compared the differences of the stream field,comprehensively investigated vortex shedding characteristics,lift and drag coefficient,distribution of mean pressure coefficients of different cross sections along the circumferential direction,pulsation of pressure coefficient of key points and vortex detachment,explained the differences of the hydrodynamic characteristics when joining the floater under the action of uniform current.This thesis established three-dimensional viscidity numerical wave tanks based on OpenFOAM's wave maker tool waves2 Foam,investigated wave making effect and wave force prediction ability of small scale pile of the tanks,the result is correct,the reliability of the numerical model is proved.On this foundation,numerically simulated the cylinder-floater system.In different wave parameters,had a detailed review of the influence on system's loads when joining the fixed floater and oscillating floater and researched on the response characteristics of oscillating floater motion.Then this thesis designed two larger oscillating floaters,compared with the original oscillating floater,obtained the effects of the size to the wave loads of floater itself and the system,it also compared the different oscillating floaters' response characteristics of motion.This thesis' s numerical experimentation also had a try to explore the vortex shedding characteristics of the cylinder and cylinder-floater system.Researched on the relationship between vortex shedding and Keulegan-Carpenter number and compared the vortex pattern and transverse wave force of the cylinder and cylinder-floater systemThis thesis also had a further research on the influence of system's loads under the extreme sea conditions by physical model test,what is more,the reliability of the numerical model is verified and the frequency domain characteristic of the transverse force is discussed emphatically.