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Vortex-Induced Vibrations of Structures

Citation

Hall, Shawn Anthony (1981) Vortex-Induced Vibrations of Structures. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Y4QP-A998. https://resolver.caltech.edu/CaltechTHESIS:02222018-150519570

Abstract

Vortex-induced oscillations, often of concern when a bluff structure is exposed to fluid cross-flow, are considered herein using a semi-empirical modeling approach. Based on the fluid momentum theorem, the model involves a highly simplified abstraction of the complex flow field, and major assumptions concerning the nature of the coupling between the fluid and the oscillating structure.

Three prototype problems are studied, including harmonically forced cylinders, spring-mounted cylinders, and taut elastic cables; in each case the structure is assumed to be of circular cross-section and situated in a uniform cross-flow. Only oscillations transverse to the flow are considered. The problem of modal interaction for elastic cables, typically of interest when the fluid flow excites high-mode-number resonances, is given particular attention.

The model produces a set of nonlinear, ordinary differential equations describing the coupled fluid/structure oscillations. Steady-state oscillatory solutions to these equations are found analytically and are examined for stability. Using various regression techniques, the steady-state solutions are then fit to experimental data for forced and spring-mounted cylinders. Finally, the model's predictions for elastic cables are used to postulate a qualitative picture of modal interaction, certain features of which have been observed experimentally.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Mechanical Engineering
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Iwan, Wilfred D.
Thesis Committee:
  • Iwan, Wilfred D. (chair)
  • Housner, George W.
  • Hudson, Donald E.
  • Sabersky, Rolf H.
  • Lorden, Gary A.
Defense Date:22 December 1980
Funders:
Funding AgencyGrant Number
NSFUNSPECIFIED
CaltechUNSPECIFIED
Record Number:CaltechTHESIS:02222018-150519570
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:02222018-150519570
DOI:10.7907/Y4QP-A998
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10729
Collection:CaltechTHESIS
Deposited By: Benjamin Perez
Deposited On:27 Feb 2018 16:11
Last Modified:16 Mar 2020 18:23

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