UNDERSTANDING FLOW-INDUCED VIBRATIONS. PART II--FLUID/STRUCTURE COUPLING; DESIGN CONSIDERATIONS

In Part I of this article the Author, after explaining the basic concepts of flow-induced vibration, discussed fluid excitation forces, which exist independently of structural motion. In this second (and concluding) part of the article, he discusses fluid/structure coupling forces, which result when a structure, excited by fluid or other external forces, vibrates within a fluid environment. These coupling forces, which vanish if there is no motion, depend on the structure and on adjacent structures and boundaries; they can significantly alter the vibration characteristics of a component, particularly if it vibrates in a confined region, and they can also lead to instabilities. The theory of these fluid/structure coupling forces is examined, together with added mass and damping of structures in liquids. Fluid flow in tubes (a common example of fluid/structure coupling leading to instability), wind-induced "galloping" of electricity transmission lines, subspan oscillations of these lines, and fluid-elastic whirling of tube rows and bundles, are all discussed in relation to the fluid/structure coupling phenomenon. In his concluding remarks, on both fluid excitation and fluid/structural coupling, the Author considers these phenomena from the design viewpoint. Prototype testing, though very desirable, is often impracticable because of the size of the structure (e.g., in the case of buildings, bridges, reactors, and offshore oil-rigs). General analytical prediction methods are lacking, and knowledge of the phenomena is fragmented and incomplete, but the designer should take full advantage of the present state of the art. He should strive for high structural-resonance frequencies, low flow-velocities, high structral damping, favourable structural geometries, and the avoidance of the more serious of the possible excitation mechanisms; each of these factors is discussed.

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  • Corporate Authors:

    Acoustical Publications, Incorporated

    27101 East Oviatt Road
    Bay Village, OH  USA  44140
  • Authors:
    • Wambsganss, M W
  • Publication Date: 1977-4

Media Info

  • Features: References;
  • Pagination: 3 p.
  • Serial:
    • SOUND AND VIBRATION
    • Volume: 11
    • Publisher: Acoustical Publications, Incorporated
    • ISSN: 0038-1810

Subject/Index Terms

Filing Info

  • Accession Number: 00172950
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: Apr 12 1978 12:00AM