EXPERIMENTAL INVESTIGATIONS OF FREE VIBRATIONS OF CYLINDER IN WATER NEAR A PLANE BOTTOM

Free vibrations of a horizontal cylinder placed in a water tank close to the plane bottom were investigated. The cylinder had four degrees of freedom, namely displacements and rotations in the horizontal and vertical planes. The accelerations of both ends of the cylinder were measured in the vertical and horizontal direction. The experimental set-up had a very small damping. Several values of the gap between the cylinder and the bottom were considered, and such values of the initial displacements were taken that the interaction with the bottom could be detected without the cylinder hitting the bottom. Assuming potential flow of inviscid and incompressible fluid, with perfect boundary conditions, and small displacements and rotations in the vertical plane, a theoretical description of the undamped dynamics of the cylinder was established. The Kalman filter method was applied to decompose the vibrations into the components having dominant frequencies. The frequencies of these components and amplitudes were compared with the results of the theoretical investigation. The theoretical solution gives proper frequencies of the components of free vibrations, except for the initial stage of vibrations when the real mechanical system needs time to develop a full coupled vibration with the fluid. The damping cannot be described only by linear terms in the differential equations.

  • Supplemental Notes:
    • J Fluids and Structures, v 9 n 7, Oct 1995, p 715 [13 p, 7 ref, 14 fig]
  • Authors:
    • Wilde, P
    • Sobierajski, E
    • Kozakiewicz, A
  • Publication Date: 1995

Language

  • English

Subject/Index Terms

Filing Info

  • Accession Number: 00718513
  • Record Type: Publication
  • Source Agency: British Maritime Technology
  • Files: TRIS
  • Created Date: Mar 27 1996 12:00AM