【作者】 苏国；

【导师】 唐锦春； 陈水福；

【作者基本信息】 浙江大学 ， 结构工程， 2007， 博士

【摘要】 高柔结构的风致振动问题是一个典型的风与结构相互作用的问题。在某些情况下代表阻尼作用的气动力可能由表现为正阻尼转变为负阻尼，若结构从风力中吸收的能量超过了其自身的阻尼耗能，则结构将发生发散式的失稳振动，这种振动现象又称为横风向驰振或颤振。由于高柔结构的发散式失稳振动容易导致结构在短时间内发生破坏，国内外研究者对这种振动的发生条件、作用机理、参数识别、计算方法等进行了多方面的研究。但是由于问题本身的复杂性以及研究条件和研究方法的局限等，迄今对不同形式失稳振动的发生机制特别是与气流形态相关的作用机理还缺乏深入的揭示和理解。本文的主要目的是通过计算流体动力学(CFD)的数值模拟方法，研究矩形截面钝体高柔结构(超高层建筑或高耸结构)风致横风向失稳式振动(驰振)的空气动力学和气动弹性力学特性以及激发这些失稳振动的气流形态和作用机理。为反映结构运动对流动风场的影响，本文除建立固定不动的计算区域外，还建立一个所谓的物理区域，该区域随着结构运动在每一时间步均同时发生运动，而计算区域是固定不变的。通过坐标变换将物理区域中的流动风场控制微分方程变换到计算区域中，即可建立引入结构运动影响的流动风场控制方程。结构本身简化为等截面的竖直刚体，其整体弹性特性通过底部假想的弹性支座实现，求解过程中，对流动风的控制方程和结构运动方程在每一时间步中进行交替和独立求解，各方程中的相互作用部分在每一时间步上得到更新，以此模拟结构与风的相互作用。本文基于结构化正交网格，采用变量同位存储的同位网格体系和标准SGS大涡模型，研制开发了建筑物绕流风场的数值模拟程序WSSG。程序采用FORTRAN语言编制，可以模拟矩形截面钝体高柔结构(超高层建筑或高耸结构)风致横风向失稳式振动(驰振)的空气动力学和气动弹性力学特性，以及激发这些失稳振动的气流形态和作用机理等，适用于三维计算。采用编制的数值模拟程序首先对静止钝体结构绕流风场进行了计算，结果表明本文的程序可以准确模拟建筑物表面的平均风压和脉动风压，并且可以获得风场结构分布。然后将该程序应用到高柔结构的风致横风向失稳式振动数值模拟中，成功捕捉到结构在风场作用下的驰振现象，并从气流形态和流场结构等方面分析了引发这种振动的机理。在此基础上，论文还研究了结构从稳定振动向失稳振动的过渡形式，以及结构弹性参数对失稳振动的影响规律。更多还原

【Abstract】 The wind-induced oscillation of flexible high-rise is a typical wind-structure interaction problem. In the process of the interaction, flow actions act as positive damp to the movement currently, but, they could transform to negative damp sometimes. If energy obtained from the flow exceeds the structure’s damp, unstable aerodynamic phenomena would occur. The unstable aerodynamic phenomena is so-called galloping or flutter, and it can destroy structures in short-term. There have a lot of studies about unstable aerodynamics in recent years, but the physical mechanism isn’t discovered now, because of its complication and limitation of study-means. The primary objective of this dissertation is to research the unstable aerodynamic characteristic and the physical mechanism of flexible high-rise with rectangular section by the Computational Fluid Dynamics (CFD).To introduce into the influence of the structure’s oscillations, a computation domain and a physical domain are established in this research. The physical domain moves with the motion of the body at each time step, although that of computational domain is fixed. The original governing equations of fluid flow in the physical domain are transformed to the computational domain’s coordinate system including time. The structure is reduced to a uniform rectangular cylinder, and is elastically mounted at the bottom. The governing equations of fluid flows and the equation of motion are alternately solved at each time step.With the convenience of nonstaggered grid system and the Smagorinsky model based on the structured orthogonal grid scheme, a computer program named WSSG is developed. Using the program can simulate the unstable aerodynamic characteristic and the physical mechanism of flexible high-rise with rectangular section. The program is employed in three-dimensional numerical simulation of wind flow.Using the developed computer program the wind flow around a static rectangular-section tall building is numerical predicted, firstly. It is proved that the mean pressure and the fluctuational pressure are computed accurately, and the flow structure can be simulated. Then, using the program the unstable aeroelastic oscillation of flexible high-rise is simulated. The galloping phenomena are achievedsuccessfully, and illustrate the physical mechanism by means of flow structure. The transition of oscillation from stable motion to unstable motion is studied. Finally, The influence of structure’s elastic-parameter to the unstable motion is researched.更多还原