Complex but negligible: non-linearity of the inertial coupling between the platform and blades of floating wind turbines
View / Open Files
Publication Date
2019-04-01Journal Title
Renewable Energy
ISSN
0960-1481
Publisher
Elsevier
Volume
134
Pages
710-726
Type
Article
This Version
AM
Metadata
Show full item recordCitation
Lupton, R., & Langley, R. (2019). Complex but negligible: non-linearity of the inertial coupling between the platform and blades of floating wind turbines. Renewable Energy, 134 710-726. https://doi.org/10.1016/j.renene.2018.11.036
Abstract
Approximate linearised models can be important for preliminary design of floating wind turbines, but their value depends on how well they approximate the real-world non-linear behaviour. This paper focuses on the non-linear inertial coupling between motion of the floating platform and the blade dynamics, using a simplified model to demonstrate how the inertial coupling works, and systematically studying the linearity of the dynamic blade response to different directions, amplitudes and frequencies of motion. Simplified equations of motion are derived and approximately solved analytically, showing that the blade response contains harmonics at a range of frequencies, some linear and some non-linear in the amplitude of the platform motion. Comparison to numerical simulations shows that the analytical results were qualitatively useful but inaccurate for large platform motions. Because of the multiple harmonics in the response, there are more combinations of rotor speeds and platform motions leading to large resonant blade responses and non-linear behaviour than might be expected. Overall, for realistically low rotor speeds and platform frequencies (below 20 rpm and 0.2 Hz), non-linear inertial loading due to platform motion should be negligible. The implications of this work for the use of linearised structural models and the relevance of scale model testing are discussed.
Sponsorship
This work was funded by an EPSRC doctoral training award (ref. 1089390)
and supported by GL Garrad Hassan.
Funder references
EPSRC (1089390)
Identifiers
External DOI: https://doi.org/10.1016/j.renene.2018.11.036
This record's URL: https://www.repository.cam.ac.uk/handle/1810/286954
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International
Licence URL: http://creativecommons.org/licenses/by-nc-nd/4.0/
Statistics
Total file downloads (since January 2020). For more information on metrics see the
IRUS guide.