Rapid optimization of stall-regulated wind turbine blades using a frequency-domain method: Part 1, loads analysis

Wind Energy ◽  
2014 ◽  
Vol 18 (10) ◽  
pp. 1703-1723 ◽  
Author(s):  
Karl O. Merz

1996 ◽  
Vol 118 (4) ◽  
pp. 204-211 ◽  
Author(s):  
H. J. Sutherland

The fatigue analysis of a wind turbine blade typically depends on converting time-series data to a series of load cycles using one of several cyclic counting algorithms. However, many structural analysis techniques yield frequency-domain stress spectra, and a large body of experimental loads (stress) data is reported in the frequency domain. To permit the fatigue analysis of this class of data, a series of computational algorithms based on Fourier analysis techniques has been developed. The principle underlying these algorithms is the use of an Inverse Fast Fourier Transform (FFT) to transform the frequency spectrum to an equivalent time series suitable for cycle counting. In addition to analyzing the fatigue loads along the primary blade axes, this analysis technique also permits the examination of “off-axis” bending loads. These algorithms, which have been incorporated in the LIFE2 fatigue analysis code for wind turbines, are illustrated and evaluated with data from typical wind turbine blades.



Author(s):  
Marit I. Kvittem ◽  
Torgeir Moan

The current paper addresses a study of a semi-submersible wind turbine, where tower base bending moments and short term tower fatigue damage was estimated by a frequency domain method assuming two-dimensional platform motions. Both a rigid structure assumption and a generalised degree of freedom model for including the first flexible mode of the turbine were investigated. First, response wind- and wave loads were considered separately, then superposition was used to find the response to combined wind and wave loading. The bending moments and fatigue damage obtained by these methods were compared to results from a fully coupled, non-linear time domain analyses. In this study a three column, catenary moored semi-submersible with the NREL 5MW turbine mounted on one of the columns was modelled. The time domain simulation tool used was Simo-Riflex-AeroDyn from Marintek and CeSOS. The frequency domain method accounting for a flexible turbine gave a good representation of the tower base bending moment histories for the moderate sea states in these analyses, also for the combined wind and wave analyses. The frequency domain fatigue damage predictions were underestimated by 0–60%, most likely due to the exponential relationship between damage and stress amplitude.



2009 ◽  
Vol 129 (5) ◽  
pp. 689-695
Author(s):  
Masayuki Minowa ◽  
Shinichi Sumi ◽  
Masayasu Minami ◽  
Kenji Horii






2021 ◽  
Author(s):  
Aileen G. Bowen Perez ◽  
Giovanni Zucco ◽  
Paul Weaver


Author(s):  
Salete Alves ◽  
Luiz Guilherme Vieira Meira de Souza ◽  
Edália Azevedo de Faria ◽  
Maria Thereza dos Santos Silva ◽  
Ranaildo Silva


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