Experimental investigation of freak wave actions on a floating platform and effects of the air gap

Min  Luo; Matteo Rubinato; Xin Wang; Xizeng Zhao

doi:10.1016/j.oceaneng.2022.111192

Experimental investigation of freak wave actions on a floating platform and effects of the air gap

Min Luo, Matteo Rubinato, Xin Wang, Xizeng Zhao

Research output: Contribution to journal › Article › peer-review

23 Citations (Scopus)

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Abstract

Unpredictable freak waves can reach up to 30 m and pose constantly a significant threat to shipping and oil/gas platforms. To provide further insights into the effects of freak waves on oceanic floating platforms, the present study conducts an experimental campaign focusing on two air-gap conditions (i.e. 0.35Hc and 0.2Hc, where Hc is the height of the platform column) and various wave impact patterns. Multiple quantities have been measured for each experimental test, including platform motions, tension forces in tethers and the wave impact pressure at numerous locations within the structure. By combining the experimental data of the air gap 0.55Hc presented in the authors’ previous study, systematic comparisons were carried out for elaborating the characteristics of impact pressures, platform motions and tether forces, as well as the effects of air gap on these quantities. Within the experimental cases tested it is found that: i) with the reduction of the air gap, the impact pressure at the bottom wall of the upper deck increases while those at the vertical front wall reduce; ii) the air gap of 0.55Hc registers larger surge motions as compared to other air-gap conditions due to the combined effect of larger horizontal loads applied on the platform and the small resistance force of the system.

Original language	English
Article number	111192
Number of pages	14
Journal	Ocean Engineering
Volume	253
Early online date	4 May 2022
DOIs	https://doi.org/10.1016/j.oceaneng.2022.111192
Publication status	Published - 1 Jun 2022

Bibliographical note

© 2022, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/

Copyright © and Moral Rights are retained by the author(s) and/ or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. This item cannot be reproduced or quoted extensively from without first obtaining permission in writing from the copyright holder(s). The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the copyright holders.

This document is the author’s post-print version, incorporating any revisions agreed during the peer-review process. Some differences between the published version and this version may remain and you are advised to consult the published version if you wish to cite from it.

Funder

The work was supported by the National Natural Science Foundation of China (Grant No. 51979245 ), the Fundamental Research Funds for the Central Universities (No. 2021QNA4036 ), the start-up funding provided by Zhejiang University (to the first author), and the research grant sponsored by the Singapore Maritime Institute and Sembcorp Marine Technology Pte Ltd (No. SMI-2014-OF-02 ).

Funding

Funders	Funder number
Sembcorp Marine Technology Pte Ltd	SMI-2014-OF-02
National Natural Science Foundation of China	51979245
Fundamental Research Funds for the Central Universities	2021QNA4036

Keywords

Freak wave
Air gap
Floating platform
Wave impact
Platform motion
Tether force

Access to Document

10.1016/j.oceaneng.2022.111192

Post PrintAccepted author manuscript, 5.37 MBLicence: CC BY-NC-ND

Cite this

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title = "Experimental investigation of freak wave actions on a floating platform and effects of the air gap",

abstract = "Unpredictable freak waves can reach up to 30 m and pose constantly a significant threat to shipping and oil/gas platforms. To provide further insights into the effects of freak waves on oceanic floating platforms, the present study conducts an experimental campaign focusing on two air-gap conditions (i.e. 0.35Hc and 0.2Hc, where Hc is the height of the platform column) and various wave impact patterns. Multiple quantities have been measured for each experimental test, including platform motions, tension forces in tethers and the wave impact pressure at numerous locations within the structure. By combining the experimental data of the air gap 0.55Hc presented in the authors{\textquoteright} previous study, systematic comparisons were carried out for elaborating the characteristics of impact pressures, platform motions and tether forces, as well as the effects of air gap on these quantities. Within the experimental cases tested it is found that: i) with the reduction of the air gap, the impact pressure at the bottom wall of the upper deck increases while those at the vertical front wall reduce; ii) the air gap of 0.55Hc registers larger surge motions as compared to other air-gap conditions due to the combined effect of larger horizontal loads applied on the platform and the small resistance force of the system.",

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N2 - Unpredictable freak waves can reach up to 30 m and pose constantly a significant threat to shipping and oil/gas platforms. To provide further insights into the effects of freak waves on oceanic floating platforms, the present study conducts an experimental campaign focusing on two air-gap conditions (i.e. 0.35Hc and 0.2Hc, where Hc is the height of the platform column) and various wave impact patterns. Multiple quantities have been measured for each experimental test, including platform motions, tension forces in tethers and the wave impact pressure at numerous locations within the structure. By combining the experimental data of the air gap 0.55Hc presented in the authors’ previous study, systematic comparisons were carried out for elaborating the characteristics of impact pressures, platform motions and tether forces, as well as the effects of air gap on these quantities. Within the experimental cases tested it is found that: i) with the reduction of the air gap, the impact pressure at the bottom wall of the upper deck increases while those at the vertical front wall reduce; ii) the air gap of 0.55Hc registers larger surge motions as compared to other air-gap conditions due to the combined effect of larger horizontal loads applied on the platform and the small resistance force of the system.

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Experimental investigation of freak wave actions on a floating platform and effects of the air gap

Abstract

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