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首页> 外文学位 >VORTEX SHEDDING FROM A VIBRATING CABLE WITH ATTACHED SPHERICAL BODIES IN A LINEAR SHEAR FLOW.
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VORTEX SHEDDING FROM A VIBRATING CABLE WITH ATTACHED SPHERICAL BODIES IN A LINEAR SHEAR FLOW.

机译：带有线性球体流的带有固定球体的振动电缆的涡旋切丝。

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摘要

Marine cables often comprise an integral part of a larger structural system, such as an offshore drilling platform. They are also used to support marker buoys, as well as anchored or towed instrument arrays. Consequently, the resonant flow-induced oscillation of these cables, caused by vortex shedding, is extremely undesirable because of the associated damaging phenomena.; The present study, which employs hot wire anemometry as the principal investigative tool, was undertaken to examine the behavior in the near wake of a flexible, helically wound, high aspect ratio (L/d = 107) marine cable in a linear shear flow (steepness parameter (beta) = 0.0053) at centerline Reynolds numbers between 2.0 x 10('3) (LESSTHEQ) Re(,c) (LESSTHEQ) 4.2 x 10('4).; Particular attention was paid to lock-on or "synchronization" related changes associated with uniform and sheared flow past the cable when it was forced to vibrate in the first mode. The study was extended to include an analysis of the effects on vortex shedding synchronization phenomena generated by placing spherical bluff bodies along the cable span.; The frequency and reduced velocity boundaries of the lock-on regions, for both the cable and sphere-cable combination, as a function of vibration amplitude up to a/d = 0.322, were measured, plotted and analyzed. The critical reduced velocity of the vibrating cable was; (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI); and for the sphere-cable combination; (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI); A sudden increase in the vortex formation length in the near wake of the vibrating cable occurred during perfect synchronization; (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI); Shortly thereafter, the formation length returned to stationary cable values.; At Re(,c) = 2.96 x 10('3), the spanwise vortex shedding frequencies behind the stationary and vibrating cable in a linear shear flow (with and without the presence of spherical bluff bodies) were measured, plotted and the results compared. A stable cellular vortex shedding frequency structure, strengthened by the synchronous vibration, existed along the span of the cable. The presence of the spacing between the spherical bodies along the cable span significantly affected the spanwise character of the near wake cellular structure. The length of the locked-on region was substantially increased (almost doubled) when the spherical bodies were present along the span of the cable.
机译：船用电缆通常构成较大结构系统（例如海上钻井平台）的组成部分。它们还用于支撑标记浮标，以及锚定或拖曳的仪器阵列。因此，由于相关的破坏现象，由涡流脱落引起的这些电缆的共振流致振荡是非常不希望的。本研究采用热线风速仪作为主要研究工具，旨在研究线性剪切流中柔性，螺旋缠绕，高纵横比（L / d = 107）的船用电缆在近尾时的行为（ ；在中心线雷诺数在2.0 x 10（'3）（LESSTHEQ）Re（，c）（LESSTHEQ）4.2 x 10（'4）之间的陡度参数（beta = 0.0053）。当电缆在第一模式下被迫振动时，特别注意锁定或“同步”相关的变化，这些变化与穿过电缆的均匀剪切流有关。该研究扩展到包括对通过沿电缆跨距放置球形钝体而产生的涡旋脱落同步现象的影响的分析。测量，绘制和分析电缆和球形电缆组合的锁定区域的频率边界和减小的速度边界，作为振动幅度的函数，直至a / d = 0.322。振动电缆的临界降低速度为； （省略了图表，表格或图形...请参见DAI）;对于球形电缆组合； （省略了图表，表格或图形...请参见DAI）;完美同步期间，在振动电缆的近尾处，涡流形成长度突然增加； （省略了图表，表格或图形...请参见DAI）;此后不久，地层长度恢复到固定的电缆值。在Re（，c）= 2.96 x 10（'3）的情况下，测量并绘制线性剪切流（有或没有球形钝体）在固定电缆和振动电缆后面的展向涡旋脱落频率，并作图比较，并将结果进行比较。沿电缆的跨度存在一个稳定的细胞涡旋脱落频率结构，该频率结构由同步振动增强。沿着电缆跨度的球形体之间的间距的存在显着影响了近尾蜂窝结构的跨度特性。当沿电缆的跨度存在球形体时，锁定区域的长度实质上增加（几乎增加了一倍）。

著录项

  • 作者

    PELTZER, RODNEY DREW.;

  • 作者单位

    Virginia Polytechnic Institute and State University.;

  • 授予单位 Virginia Polytechnic Institute and State University.;
  • 学科 Engineering Civil.
  • 学位 Ph.D.
  • 年度 1982
  • 页码 182 p.
  • 总页数 182
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 建筑科学;
  • 关键词

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