Measuring Hydroelastic Deformation of Very Flexible Floating Structures

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Abstract

For Offshore Floating Photovoltaics (OFPV) applications, thin-film PV panels on lightweight floating support structures gain increasing scientific and commercial interest. Over the past years, several different concepts of thin-film OFPV have been proposed, with the common denominator of floating mattress or blanket-like support structures with very little draft in the order of centimeters compared to their width and length in the order of several tens to hundreds of meters. Mostly made from polymer foam materials, these floating support structures are more flexible than the conventional Very Large Floating Structures (VLFS) investigated in 1990s. The flexibility of a floating structure is expressed by the characteristic length derived from the ratio of the structural bending stiffness and the hydrostatic stiffness of the support. For conventional VLFS, this characteristic length is usually longer than the dominant wavelength of the ocean waves, resulting in only moderate structural deflections of the order of 1/10 of the wave height and the total thickness of the structure. The newly proposed structures have characteristic lengths of less than the wavelength of ocean waves. This allows the structures to move with the waves and follow the wave elevation like a floating blanket. Therefore, these structures are classified as Very Flexible Floating Structures (VFFS). Despite the growing interest in VFFS, little is still known about their hydroelastic deformation and their influence on the surrounding wave field. To start the experimental VFFS research at Delft University of Technology, Digital Image Correlation (DIC) measurements were carried out in this study to investigate the vertical deflection of a VFFS at model scale in a small towing. The model’s characteristic length was 1/3 of the shortest wavelength and it was tested in long-crested regular longitudinal waves. The wavelength varied between 1/10 and 1/5 of the structure length. The measurements showed that the structure indeed mostly followed the wave elevation and revealed 3D effects across the structure, which require deeper investigation into wave scattering of VFFS.

Original languageEnglish
Title of host publicationProceedings of the 2nd World Conference on Floating Solutions, WCFS2020
EditorsLukasz Piatek, Soon Heng Lim, Chien Ming Wang, Rutger de Graaf-van Dinther
Place of PublicationSingapore
PublisherSpringer
Pages347-371
ISBN (Electronic)978-981-16-2256-4
ISBN (Print)978-981-16-2255-7
DOIs
Publication statusPublished - 2022
Event2nd World Conference on Floating Solutions, WCFS 2020: Paving the Waves - Virtual, Online, Netherlands
Duration: 6 Oct 20208 Oct 2020

Publication series

NameLecture Notes in Civil Engineering
Volume158
ISSN (Print)2366-2557
ISSN (Electronic)2366-2565

Conference

Conference2nd World Conference on Floating Solutions, WCFS 2020
CountryNetherlands
CityVirtual, Online
Period6/10/208/10/20

Bibliographical note

Accepted Author Manuscript

Keywords

  • Digital image correlation (DIC)
  • Hydroelasticity
  • Offshore floating PV
  • Very flexible floating structures (VFFS)
  • Wave scattering

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