【作者】 徐枫；

【导师】 欧进萍；

【作者基本信息】 哈尔滨工业大学 ， 工程力学， 2009， 博士

【摘要】 现代结构向超高层和大跨度方向发展,使结构变轻、变柔,结构在风荷载作用下的流固耦合效应十分突出。深入系统地研究结构流固耦合效应及其流场主动控制方法与机理,具有重要的学术价值和广阔的应用前景。本文采用CFD数值模拟方法,研究结构/群的涡激振动及其绕流场控制原理,揭示湍流来流条件下结构涡激振动的特点和规律,并将研究成果应用于实际超高层建筑结构绕流场及其风致振动效应的分析中。本文的主要研究内容如下:首先,在Fluent流体计算平台基础上,在C语言下自编结构域振动程序(采用Newmark-β算法),并通过动网格技术更新边界,发展一种弹性支撑刚性柱体流致振动的数值模拟计算方法。在此基础上,研究不同截面形状柱体的振动特点,分析结构参数和流向振动对圆柱气动力和位移的影响规律,给出尾流涡结构,揭示柱体振动与涡脱模式间的关系。第二,建立弹性支撑圆柱群流固耦合振动系统的数值计算方法;研究正方形顺排排列四圆柱的固定绕流干扰效应,以及间距对各圆柱气动力及频率特性的影响;进一步研究弹性支撑四圆柱的气动弹性干扰效应,分析间距对各圆柱的气动力和振动响应的影响规律,揭示流场结构与涡脱模式。第三,研究表面带振荡附属物的单圆柱涡激振动,建立表面带振荡附属物的单圆柱涡激振动模型,分析附属物的尺寸、旋转方向和振荡幅度对圆柱涡激振动幅值的影响,分析气动力和位移随折减风速的变化规律及与附属物振荡方向的相关性。第四,研究CFD数值模拟中湍流来流边界的实现方法,通过单圆柱的绕流结果揭示出流场的脉动特性,进一步研究不同湍流强度脉动风作用下单圆柱的涡激振动,重点分析圆柱的位移幅值和锁定区范围随折减风速的变化规律,指出与平均风作用下单圆柱涡激振动结果的差别并分析产生差别的原因。第五,将本文实现的脉动风来流边界应用于实际工程结构,基于数值风洞技术预测超高层建筑表面的平均风压和脉动风压,并与风洞实验结果进行比较;进一步对超高层建筑的风致流固耦合振动进行数值模拟,并与常态风和台风作用下该超高层建筑的现场实测结果进行对比,重点分析了结构的振动响应和气动力随高度和时间的变化规律,通过不同高度处的涡量等值线图分析结构振动对流场的影响。最后,采用角动量尾迹控制法对固定方柱绕流场实现主动流动控制,研究不同风向和角动量大小对流场的控制效果;进一步研究了角动量尾迹控制法对弹性支撑方柱单自由度横向振动的抑制,通过方柱表面的平均压力分布和尾流涡量等值线图揭示该方法实现流动控制的机理。更多还原

【Abstract】 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.更多还原