Simplified rotor load models and fatigue damage estimates for offshore wind turbines

Muskulus, Michael

doi:10.1098/rsta.2014.0347

Cited by 13 publications

(11 citation statements)

References 21 publications

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“…1). It is important to use a rigidly clamped rotor, since load time series from a simulation with moving support structure will lead to resonance problems (Muskulus, 2015b). Rotor load time series are then extracted from turbine bottom and applied at the top of the tower to perform a dynamic analysis of the support structure using standard finite-element or multi-body software.…”

Section: Integrated and Decoupled Dynamic Analysismentioning

confidence: 99%

Response to referee 1

Anonymous

2017

Preprint

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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 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.

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Section: Integrated and Decoupled Dynamic Analysismentioning

confidence: 99%

Response to referee 1

Anonymous

2017

Preprint

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“…In the theme issue, the papers by Muskulus [55] and by Alati et al [56] present numerical studies on offshore wind turbines under normal and extreme loading conditions of particular interest.…”

Section: Design Load Casesmentioning

confidence: 99%

“…Muskulus [55] carries out a comparative analysis of some simplified analytical models of rotor thrust, with special focus on their suitability for fatigue life assessment of the baseline NREL 5 MW wind turbine [44] mounted on a jacket. Simplified rotor load models provide loads to be applied to a standard FE model of the support structure, in approximation of the actual rotor loads that would be obtained from a fully coupled time-domain simulation.…”

Section: Design Load Casesmentioning

confidence: 99%

New perspectives in offshore wind energy

Failla

Arena

2015

Phil. Trans. R. Soc. A.

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The design of offshore wind turbines is one of the most fascinating challenges in renewable energy. Meeting the objective of increasing power production with reduced installation and maintenance costs requires a multi-disciplinary approach, bringing together expertise in different fields of engineering. The purpose of this theme issue is to offer a broad perspective on some crucial aspects of offshore wind turbines design, discussing the state of the art and presenting recent theoretical and experimental studies.

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“…1). Rotor loads are typically precomputed or generated by means of simplified rotor load models, such as classical models based on thrust coefficients or spectral or stochastic models (Muskulus, 2015a). Precomputed rotor loads are usually obtained from an aeroelastic simulation of a standalone turbine fixed at turbine bottom or from a wind turbine with non-moving, rigid support structure ( Fig.…”

Section: Integrated and Decoupled Dynamic Analysismentioning

confidence: 99%

Decoupled simulations of offshore wind turbines with reduced rotor loads and aerodynamic damping

Schafhirt

Muskulus

2018

Wind Energ. Sci.

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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 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.

show abstract

Simplified rotor load models and fatigue damage estimates for offshore wind turbines

Cited by 13 publications

References 21 publications

Response to referee 1

Response to referee 1

New perspectives in offshore wind energy

Decoupled simulations of offshore wind turbines with reduced rotor loads and aerodynamic damping

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