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首页> 外文学位 >The Aerodynamic and Dynamic Loading of a Slender Structure by an Impacting Tornado-Like Vortex: The Influence of Relative Vortex-to-Structure Size on Structural Loading.
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The Aerodynamic and Dynamic Loading of a Slender Structure by an Impacting Tornado-Like Vortex: The Influence of Relative Vortex-to-Structure Size on Structural Loading.

机译：像冲击龙卷风一样的细长结构的气动和动态载荷：相对涡流至结构的大小对结构载荷的影响。

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摘要

Structural loading produced by an impacting vortex is a hazardous phenomenon that is encountered in numerous applications ranging from the destruction of residences by tornados to the chopping of tip vortices by rotors. Adequate design of structures to resist vortex-induced structural loading necessitates study of the phenomenon that control the structural loading produced by an impacting vortex. This body of work extends the current knowledge base of vortex-structure interaction by evaluating the influence of the relative vortex-to-structure size on the structural loading that the vortex produces. A computer model is utilized to directly simulate the two-dimensional impact of an impinging vortex with a slender, cylindrical structure. The vortex's tangential velocity profile (TVP) is defined by a normalization of the Vatistas analytical (TVP) which realistically replicates the documented spectrum of measured vortex TVPs. The impinging vortex's maximum tangential velocity is fixed, and the vortex's critical radius is incremented from one to one-hundred times the structure's diameter. When the impinging vortex is small, it interacts with vortices produced on the structure by the free stream, and maximum force coefficient amplitudes vary by more than 400% when the impinging vortex impacts the structure at different times. Maximum drag and lift force coefficient amplitudes reach asymptotic values as the impinging vortex's size increases that are respectively 94.77% and 10.66% less than maximum force coefficients produced by an equivalent maximum velocity free stream. The vortex produces maximum structural loading when its path is shifted above the structure's centerline, and maximum drag and lift force coefficients are respectively up to 4.80% and 34.07% greater than maximum force coefficients produced by an equivalent-velocity free stream. Finally, the dynamic load factor (DLF) concept is used to develop a generalized methodology to assess the dynamic amplification of a structure's response to vortex loading and to assess the dynamic loading threat that tornados pose. Typical civil and residential structures will not experience significant response amplification, but responses of very flexible structures may be amplified by up to 2.88 times.
机译：由冲击涡流产​​生的结构载荷是一种危险现象，在许多应用中都遇到，从龙卷风破坏住所到旋翼切碎尖端涡流。为抵抗涡旋引起的结构载荷而对结构进行充分的设计，有必要研究控制冲击涡旋所产生的结构载荷的现象。通过评估相对于结构的相对涡流大小对涡流产生的结构载荷的影响，本工作扩展了涡流与结构相互作用的当前知识库。利用计算机模型直接模拟具有细长圆柱结构的撞击涡流的二维冲击。涡流的切线速度曲线（TVP）由Vatistas分析（TVP）的归一化定义，该归纳法实际上复制了已记录的测量涡流TVP频谱。撞击涡流的最大切向速度是固定的，并且涡流的临界半径从结构直径的一倍增加到一百倍。当撞击涡流较小时，它会与自由流在结构上产生的涡流相互作用，并且当撞击涡流在不同时间撞击结构时，最大力系数振幅的变化幅度超过400％。当撞击涡旋的大小增加时，最大阻力和升力系数幅度达到渐近值，分别比等效最大速度自由流产生的最大力系数分别小94.77％和10.66％。当涡旋的路径移动到结构中心线上方时，涡旋会产生最大的结构载荷，并且最大阻力和升力系数分别比等速自由流产生的最大力系数大4.80％和34.07％。最后，动态载荷因子（DLF）概念用于开发一种通用方法，以评估结构对涡旋载荷响应的动态放大并评估龙卷风带来的动态载荷威胁。典型的民用和住宅结构将不会经历明显的响应放大，但是非常灵活的结​​构的响应可能会放大2.88倍。

著录项

  • 作者

    Strasser, Matthew N.;

  • 作者单位

    University of Arkansas.;

  • 授予单位 University of Arkansas.;
  • 学科 Mechanical engineering.;Civil engineering.;Aerospace engineering.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 246 p.
  • 总页数 246
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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