Parametric pitch instability investigation of Deep Draft Semi-submersible platform in irregular waves

Mao, H. and Yang, H. (2016) Parametric pitch instability investigation of Deep Draft Semi-submersible platform in irregular waves. International Journal of Naval Architecture and Ocean Engineering, 8(1), pp. 13-21. (doi:10.1016/j.ijnaoe.2015.09.001)

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Abstract

Parametric pitch instability of a Deep Draft Semi-submersible platform (DDS) is investigated in irregular waves. Parametric pitch is a form of parametric instability, which occurs when parameters of a system vary with time and the variation satisfies a certain condition. In previous studies, analyzing of parametric instability is mainly limited to regular waves, whereas the realistic sea conditions are irregular waves. Besides, parametric instability also occurs in irregular waves in some experiments. This study predicts parametric pitch of a Deep Draft Semi-submersible platform in irregular waves. Heave motion of DDS is simulated by wave spectrum and response amplitude operator (RAO). Then Hill equation for DDS pitch motion in irregular waves is derived based on linear-wave theory. By using Bubnov-Galerkin approach to solve Hill equation, the corresponding stability chart is obtained. The differences between regular-waves stability chart and irregular-waves stability chart are compared. Then the sensitivity of wave parameters on DDS parametric pitch in irregular waves is discussed. Based on the discussion, some suggestions for the DDS design are proposed to avoid parametric pitch by choosing appropriate parameters. The results indicate that it's important and necessary to predict DDS parametric pitch in irregular waves during design process.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Yang, Dr Hezhen
Authors: Mao, H., and Yang, H.
College/School:College of Science and Engineering > School of Engineering > Infrastructure and Environment
Journal Name:International Journal of Naval Architecture and Ocean Engineering
Publisher:Elsevier
ISSN:2092-6782
ISSN (Online):2092-6782
Copyright Holders:Copyright © 2016 Society of Naval Architects of Korea
First Published:First published in International Journal of Naval Architecture and Ocean Engineering 8(1):13-21
Publisher Policy:Reproduced under a Creative Commons License

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