【作者】 郑朝荣；

【导师】 倪振华； 张耀春；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2010， 博士

【摘要】 高强轻质材料的广泛应用,使得(超)高层建筑向着越来越高、越来越柔、阻尼比越来越小的方向发展,逐渐成为风敏感性结构,抗风设计已成为需重点考虑的关键因素。在强风作用下,(超)高层建筑在强度、变形和舒适度等方面的设计面临着严峻的挑战,而且其围护结构也时常遭受破坏,造成巨大损失。因此,研究(超)高层建筑风荷载的数值模拟技术,并进而研究风对(超)高层建筑的作用机理,探索采取空气动力学措施来减小风荷载和风致响应的策略和方法,具有十分重要的理论意义和实用价值。流动控制是指采取一定的局部控制措施来改变钝体或流线体周围的全局流场,从而实现控制流动分离、改善绕流性能、减小阻力和提高翼型的升阻比等目的的控制方法。流动控制被认为是当前空气动力学最有发展潜力的研究领域之一。近年来,主动流动控制方法已成为流体力学中不断受人关注的课题,其中吸/吹气控制方法已在航空航天、管道输运和流体机械等领域中被广泛应用。为减小高层建筑的风致阻力,改善结构的抗风性能,本文将均匀吸/吹气控制方法引入到建筑结构中。在对吸/吹气控制下三维后台阶的流动分离进行数值验证和确认后,采用雷诺应力方程模型(RSM)对侧风面全高或沿高度分段吸/吹气控制下高层建筑模型的风荷载减阻性能进行了数值研究,阐明了吸/吹气控制的风荷载减阻机理。此外,本文还模拟了大气边界层中“真实”的入流湍流,并采用大涡模拟(LES)方法研究了CAARC标准高层建筑刚性模型的脉动风荷载,构建了建筑结构脉动风荷载的数值模拟技术。本文主要进行了以下几方面的工作:1、分别采用基于RSM的雷诺平均Navier-Stokes(RANS)方法、基于动力Smagorinsky-Lilly模型(DSM)和动力动能亚格子模型(DKEM)的LES方法对均匀吸/吹气控制下三维后台阶的流动分离进行了定常和非定常数值模拟,并将数值结果与相应的实验数据进行了比较,确认了基于RSM的RANS方法和基于DKEM的LES方法模拟吸/吹气控制下钝体绕流的可信度,为下文研究采用均匀吸/吹气措施控制高层建筑风荷载的方法奠定基础。2、采用RSM湍流模型对侧风面全高均匀吸/吹气控制下高层建筑模型的风荷载减阻性能进行了定常数值模拟,分析了吸/吹气孔的几何参数和流量参数对风荷载减阻性能的影响,并通过展示流场结构阐明了吸/吹气控制机理。讨论了吸/吹气所消耗的功率及其产生的反作用力,并拟合了阻力折减系数CDR和顺风向基底弯矩折减系数CMR的经验公式,为全高吸/吹气控制高层建筑的实际应用提供参考。3、为解决全高吸/吹气高层建筑存在的设备安装困难、连续协同工作难以控制和影响建筑物的功能使用等缺点,采用RSM湍流模型对分段吸/吹气高层建筑模型的风荷载减阻性能进行了数值研究,基于最大风压折减效率和最小吸/吹气功率比较了分段吸/吹气模型和全高吸/吹气模型的减阻性能。回归了阻力折减效率ηDR和顺风向基底弯矩折减效率ηMR的经验公式,为分段吸/吹气控制高层建筑的实际应用提供参考。4、从控制原理、控制参数和控制效果等方面比较了吸/吹气控制实现高层建筑风荷载减阻的异同,讨论了吸/吹气控制方法在高层建筑抗风设计中的应用及其实施的可行性。5、在“真实”地模拟了大气边界层中的入流湍流基础之上,采用LES方法研究了CAARC标准模型的脉动风荷载特性,考察了数值模拟的多种参数对CAARC模型的表面风压分布特性、气动力参数和功率谱的影响。将数值计算结果与相应的风洞试验数据进行了比较,确认了入流湍流边界条件下LES方法模拟大气边界层中钝体绕流的脉动风荷载的可信度,从而为今后研究吸/吹气方法控制高层建筑的脉动风荷载和横风向的旋涡脱落特性奠定了基础。更多还原

【Abstract】 As a result of extensive utility of high-strength and light-weight materials in construction, high-rise buildings tend to be higher and more flexible, with a lower damping ratio. Therefore, they are very sensitive to the wind loads, and the wind-resistance design has gradually become the dominant factor in structural designs. Wind-resistance designs for high-rise buildings, including the aspects of strength, displacement and habitational comfort, are confronted with severe challenges under strong wind excitations, and the claddings frequently suffer from destruction, bringing substantial losses. Consequently, it is very important and necessary to investigate the numerical simulation techniques for analyzing the physical mechanisms of wind loads on high-rise buildings, and to take aerodynamic measures to reduce the wind loads and wind-induced responses.The flow control is a means to change the overall flowfield around bluff or streamlined body via using some locally aerodynamic measures, and its aim is to control the flow separation, improve the aerodynamic performance, reduce the drag and increase the lift-to-drag ratio for the airfoils. Actually, flow control is believed to be one of the most promising domains for research in the currently developed aerodynamics. In recent years, the active flow control techniques have become an increasingly attractive topic in fluid mechanics, and among them the suction or blowing method has already been widely used in domains of the aerospace, pipeline transportation and fluid machinery.In order to reduce the wind-induced drag and improve the wind-resistance performance of high-rise buildings, the continuous suction/blowing control method is introduced into the building structures. Based on verification and validation of the numerical methods by the experiment of suction/blowing control over the flow separation of a 3D backward-facing step, the Reynolds stress equation model (RSM) is used to investigate the performance of wind-load reduction for a high-rise building controlled by all-height or subsection suction/blowing on its side faces, and the mechanism of the wind-load reduction under suction/blowing control is clarified. Moreover, the“real”inflow turbulence in the atmosphere boundary layer is simulated, and the turbulence model of large eddy simulation (LES) is used to investigate the fluctuating wind loads on the rigid CAARC standard building model. Therefore, the numerical techniques for simulating the fluctuating wind loads on building structures are constructed.The main contents in the paper are shown as followings: 1. Three tuebulence models, including the Reynolds-averaged Navier-Stokes (RANS) method based on the RSM and the LES method based on the subgrid-scale stress models of the dynamic Smagorinsky-Lilly model (DSM) and dynamic kinetic energy subgrid-scale model (DKEM), are adopted to calculate flow separation of a 3D backward-facing step controlled by continuous suction/blowing, respectively. The numerical results are compared with the corresponding experiment data, and the credibility of using the RANS method based on the RSM and the LES method based on the DKEM to simulate separated flows around bluff body controlled by suction/blowing is validated. The CFD validation provides a solid foundation to correctly calculate the wind loads on a high-rise building controlled by continuous suction/blowing in the following paper.2. The performance of wind-load reduction for an all-height suction/blowing high-rise building is numerical investigated through the turbulence model of RSM. Effects of the orifice geometrical parameters and the suction/blowing flux parameters on the drag-reduction properties are analyzed, and detailed flowfields are showed to clarify the mechanism of suction/blowing control. Moreover, the power consumed and the counterforce induced by suction/blowing are discussed, and formulae for the coefficient of drag reduction (CDR) and the coefficient of along-wind base-moment reduction (CMR) are regressed, which can be referred for practical applications of the all-height suction/blowing high-rise buildings.3. In order to resolve the problems, such as installation of the suction/blowing equipments, continuous cooperations and functional usage of architectural space, induced by the all-height suction/blowing control on high-rise buildings, the performance of wind-load reduction for a high-rise building controlled by subsection suction/blowing along the height is numerical investigated through the turbulence model of RSM. The drag-reduction properties for the subsection and the all-height suction/blowing models are compared based on the maximal drag- reduction efficiencies and the minimal power consumed. Lastly, the formulae for the efficiency of drag reduction (ηDR) and the efficiency of along-wind base-moment reduction (ηMR) are regressed to be referred for practical applications of the subsection suction/blowing high-rise buildings.4. The similarities and differences between suction and blowing control to achieve the wind-load reduction for the high-rise building are compared based on the control principles, control parameters and control effects, and the feasibility of applying and implementing suction/blowing control for the wind-resistance design of high-rise buildings is discussed.5. Based on simulation of the“real”inflow turbulence in the atmosphere boundary layer, the LES method is used to investigate the characteristics of fluctuating wind loads on the CAARC standard building model, and effects of the influence parameters of numerical methods on the pressure coefficients, aerodynamic force/base-moment coefficients and power spectrum are analyzed. The numerical results are compared with the corresponding data from the wind tunnel tests, and the credibility of using the LES method together with the inflow turbulence boundary condition to simulate the fluctuating wind loads on bluff bodies in the atmosphere boundary layer is validated. Based on the studies, the ultimate aim is to investigate the fluctuating wind loads and characteristics of the crosswind vortex shedding for the suction/blowing controlled high-rise buildings in the future work.更多还原