NDLI: Nonlinear Pitch Decay of a Floating Offshore Wind Turbine Structure

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Thiagarajan, K. P. Urbina, R. Hsu, W.
Copyright Year	2013
Abstract	Model tests were conducted on three generic floating wind turbine systems in 2011, and reported in a series of papers at OMAE 2012. These tests were conducted at the MARIN facility in the Netherlands, by a consortium of universities, government research organizations and industry. As part of the testing program, decay tests in platform pitch were conducted with and without wind. It was found that for spar and semi-submersible type structures, resonant pitch motion was damped due to wind in storm sea conditions. The nonlinear decay motion of a floating wind turbine platform is modeled using a one degree-of-freedom nonlinear oscillation equation about a mean offset angle. Attention is paid to the turbine thrust coefficient and its variability with respect to oncoming flow speed, which in turn is affected by the structure pitch motion. The equation of motion reveals that the mean offset position has an important role in the stiffness, damping and consequently the natural period of pitch motion. Several important dimensionless parameters are introduced. The paper discusses a simple thrust model for an offshore wind turbine based on rudiments of blade element theory. Using the simplified thrust coefficient formulation, the increase in platform pitch damping due to wind is formulated. Experimental data reported from prior tests described above show good agreement with the theoretical model.
Sponsorship	Ocean, Offshore and Arctic Engineering Division
File Format	PDF
ISBN	9780791855423
DOI	10.1115/OMAE2013-10244
Volume Number	Volume 8: Ocean Renewable Energy
Conference Proceedings	ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering
Language	English
Publisher Date	2013-06-09
Publisher Place	Nantes, France
Access Restriction	Subscribed
Subject Keyword	Damping Wind Degrees of freedom Seas Blades Oscillations Equations of motion Flow (dynamics) Spar platforms Governments Floating wind turbines Storms Offshore wind turbines Semi-submersible offshore structures Resonance Stiffness Thrust Turbines Wing spars Testing
Content Type	Text
Resource Type	Article

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