Numerical Simulation Of Fluid-Solid Coupling Vibration And Flow Control Of Structures

Modern building structures begin to develop towards super high-rise and large span, and become more and more light and flexible. The fluid-solid coupling effect to the structure is very conspicuous under wind loads. It has important academic value and wide application prospect to systematically investigate the fluid-solid coupling effect and the active flow control method and mechanism.The computational fluid dynamics (CFD) is employed in present paper to study the vortex-induced vibration and the flow field control principle a structure/ a structure group, and reveal the characteristics and laws of vortex-induced vibration of the structure under a fluctuating inflow. Moreover, the research results are employed to analyze flow field around the structure and the wind-induced vibration of an actual super high building.The main contents are included as follows:Firstly, a computation program of the structural domain is realized through a user defined function (UDF) based a Newmark-βalgorithm in a C language environment on the Fluent numerical platform base; the boundary updating is completed through a moving-grid technology; and develop a numerical calculation method of flow-induced vibration of a rigid cylinder under an elastic support. The vibration type's characteristics of different section shapes are investigated. The influence law of structure parameters and flow-along vibration to the aerodynamic force and oscillation displacement are emphatically analyzed; the wake vortex structures are given; and the correlation between cylinder vibration and vortex shedding pattern is revealed.Secondly, this paper develops a numerical calculation method of fluid-solid interaction vibration system of multi cylinders under elastic supports. The flow interferences of four fixed circular cylinders in line square arrangements and the influence of the spacing ratios to aerodynamic forces of each cylinder and frequency characteristics are investigated. Furthermore, the flow interferences of four circular cylinders under elastic supports in line square arrangements are investigated. The influence law of the space ratio changing to the aerodynamic forces and vibration types are emphatically analyzed; and the fluid field structures and the vortex shedding patterns are revealed. Thirdly, this paper investigates the vortex induced vibration of a single cylinder with a surface rotation appendage, and set up a vortex-induced vibration model of a single cylinder with a surface rotation appendage. The influence of the size, rotation direction and rotation amplitude of the rotation appendage to the oscillation amplitude of the cylinder is emphatically studied; the changing law of the aerodynamic lift force and cross-flow displacement with the reduced velocity is analyzed; and the correlation between the aerodynamic lift force and cross-flow displacement with the rotation direction of the surface appendage is investigated.Fourthly, this paper studies a realized method of turbulent inflow boundary in the CFD numerical simulation. The fluctuating characteristics of the flow field are revealed through the flow results around a single cylinder. Furthermore, the vortex induced vibration of a single cylinder under a fluctuating wind with various turbulent intensities is investigated. The changing law of the displacement amplitude of the cylinder and frequency lock-in range with the reduced velocity is emphatically analyzed, the differences of vortex-induced vibration under a mean wind and a fluctuating wind are given and the generation reason of the differences is analyzed.Fifthly, the fluctuating inflow boundary realized in present paper is employed to an actual engineering of a super high building. The surface mean and fluctuating wind pressures on the super high building based the numerical wind tunnel technology are predicted, which are compared with the mean wind pressure results of the wind tunnel experiments. Furthermore, the fluid-solid coupling effect between the super high building and the wind field is numerically simulated and compared with the measured results under the normal wind and typhoon. The changing laws of aerodynamic forces and displacement with height and time are emphatically analyzed; and the influence of structure vibration to the fluid field is analyzed through the vorticity contours of different heights.Lastly, the angular momentum wake control method is employed to control the flow field around the fixed square cylinder, and the control effectiveness of the input size of angular momentum for the flow field under different wind yaw angles is investigated. Furthermore, the angular momentum wake control method is studied to suppress the cross-flow vibration of the square cylinder under an elastic support. The flow control mechanism using this method is revealed by analyzing the mean pressure distribution on the surface of the square cylinder and the vorticity contours in the wake.