Journal cover Journal topic
Wind Energy Science The interactive open-access journal of the European Academy of Wind Energy
https://doi.org/10.5194/wes-2017-29
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research articles
27 Jul 2017
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Wind Energy Science (WES).
Decoupled simulations of offshore wind turbines with reduced rotor loads and aerodynamic damping
Sebastian Schafhirt and Michael Muskulus Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, Trondheim, 7491, Norway
Abstract. Decoupled load simulations are a computationally efficient method to perform a dynamic analysis of an offshore wind turbine. Modelling the dynamic interactions between rotor and support structure, especially the damping caused by the rotating rotor, is of importance, since it influences the structural response significantly and has a major impact on estimating fatigue lifetime. Linear damping is usually used for this purpose, but experimentally and analytically derived formulas to calculate an aerodynamic damping ratio often show discrepancies to measurement and simulation data. In this study decoupled simulation methods with reduced and full rotor loads are compared to an integrated simulation. The accuracy of decoupled methods is evaluated and an optimization is performed to obtain aerodynamic damping ratios for different wind speeds that provide the best results with respect to variance and equivalent fatigue loads at distinct output locations. Results show that aerodynamic damping is not linear, but that it is possible to match desired output using decoupled models. Moreover, damping ratios obtained from the empirical study suggest that aerodynamic damping increases for higher wind speeds.

Citation: Schafhirt, S. and Muskulus, M.: Decoupled simulations of offshore wind turbines with reduced rotor loads and aerodynamic damping, Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2017-29, in review, 2017.
Sebastian Schafhirt and Michael Muskulus
Sebastian Schafhirt and Michael Muskulus
Sebastian Schafhirt and Michael Muskulus

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