Study On Flow Control Method For Suppressing Wake And Vortex Induced Vibration Of Flow Around A Bluff Body By Dynamic Wave Wall

Circular and square cylinders are common blunt bodies used in structures of practical engineering.Flow around blunt bodies in wind or water is a classical hydrodynamic problem involving flow separation,reattachment and vortex shedding.The dynamic load acting on the structure and vibration induced by flow around bluff body and vortex shedding become the main factors leading to structural instability or fatigue failure.Therefore,eliminating the oscillating wake and suppressing the vortex-induced vibration of the bluff body have important scientific significance and application prospects in engineering.A numerical simulation method based on computational fluid dynamics(CFD)is used to study the wake and vortex-induced vibration characteristics of typical bluff bodies such as circular and square cylinders in this research.Then the effects of flow control method with dynamic wave wall(DWW)on the wake and vortex-induced vibration suppression of square and circular cylinders are analysed.Further on,the physical mechanism of the flow control method is also revealed.The main work are carried out as follows.(1)Based on software platform Fluent,the flow characteristics of rectangular cylinders with different aspect ratios are analysed,and the variation of aerodynamic and wake vortex shedding modes with aspect ratios is obtained.Also,the fluid-structure interaction between square cylinder and flow field is simulated.And the aerodynamic and vibration response characteristics of square cylinder under different mass ratios and reduced damping parameters are analyzed to reveal the relationship between vibration response of square cylinder and wake vortex shedding mode.(2)Flow around the square cylinder with dynamic wave traveling on the side surfaces are simulated.Comparing with the results of flow around the standard squarecylinder,the control parameters of the dynamic wave wall with better control effect on the wake of the square cylinder are obtained.(3)The dynamic wave wall method is used to study the effect of wake suppression on the flow around a fixed circular cylinder.The influence of the key control parameters of the dynamic wave wall on the wake control effect is studied.And,the whole process from the flow around a fixed cylinder to the control of the moving wave wall is simulated.(4)The suppressing effect of dynamic wave wall method on vortex induced vibration of an elastic supported circular cylinder is studied.The vortex-induced vibration characteristics along and across the flow direction of both an uncontrolled cylinder and a controlled cylinder with DWW are analyzed.The numerical simulation of the whole process from the flow around the cylinder to the vortex-induced vibration,and then to the control of the moving wave wall is completed.The evolution of the aerodynamic force,vibration response and wake vortex shedding mode of the cylinder at various stages are emphatically analyzed.(5)Based on the control results of the wake flow around a cylinder with DWW,the mechanism of the method is analyzed according to the evolution law of the boundary vorticity flow,the relative flow field and the spatio-temporal correlation of the wake flow around a 3D cylinder.