OC6 Project Phase III: Validation of the Aerodynamic Loading on a Wind Turbine Rotor Undergoing Large Motion Caused by a Floating Support Structure

Bergua, Roger; Robertson, Amy; Jonkman, Jason; Branlard, Emmanuel; Fontanella, Alessandro; Belloli, Marco; Schito, Paolo; Zasso, Alberto; Persico, Giacomo; Sanvito, Andrea; Amet, Ervin; Brun, Cédric; Campaña-Alonso, Guillén; Martín-San-Román, Raquel; Cai, Ruolin; Cai, Jifeng; Qian, Quan; Maoshi, Wen; Beardsell, Alec; Pirrung, Georg; Ramos-García, Néstor; Shi, Wei; Fu, Jie; Corniglion, Rémi; Lovera, Anaïs; Galván, Josean; Nygaard, Tor Anders; dos Santos, Carlos Renan; Gilbert, Philippe; Joulin, Pierre-Antoine; Blondel, Frédéric; Frickel, Eelco; Chen, Peng; Hu, Zhiqiang; Boisard, Ronan; Yilmazlar, Kutay; Croce, Alessandro; Harnois, Violette; Zhang, Lijun; Li, Ye; Aristondo, Ander; Mendikoa Alonso, Iñigo; Mancini, Simone; Boorsma, Koen; Savenije, Feike; Marten, David; Soto-Valle, Rodrigo; Schulz, Christian; Netzband, Stefan; Bianchini, Alessandro; Papi, Francesco; Cioni, Stefano; Trubat, Pau; Alarcon, Daniel; Molins, Climent; Cormier, Marion; Brüker, Konstantin; Lutz, Thorsten; Xiao, Qing; Deng, Zhongsheng; Haudin, Florence; Goveas, Akhilesh

doi:https://doi.org/10.5194/wes-2022-74

Preprints

https://doi.org/10.5194/wes-2022-74

Preprints

23 Aug 2022

Status: a revised version of this preprint is currently under review for the journal WES.

OC6 Project Phase III: Validation of the Aerodynamic Loading on a Wind Turbine Rotor Undergoing Large Motion Caused by a Floating Support Structure

Roger Bergua¹, Amy Robertson¹, Jason Jonkman¹, Emmanuel Branlard¹, Alessandro Fontanella², Marco Belloli², Paolo Schito², Alberto Zasso², Giacomo Persico³, Andrea Sanvito³, Ervin Amet⁴, Cédric Brun⁴, Guillén Campaña-Alonso⁵, Raquel Martín-San-Román⁵, Ruolin Cai⁶, Jifeng Cai⁶, Quan Qian⁷, Wen Maoshi⁷, Alec Beardsell⁸, Georg Pirrung⁹, Néstor Ramos-García⁹, Wei Shi¹⁰, Jie Fu¹⁰, Rémi Corniglion¹¹, Anaïs Lovera¹¹, Josean Galván¹², Tor Anders Nygaard¹³, Carlos Renan dos Santos¹³, Philippe Gilbert¹⁴, Pierre-Antoine Joulin¹⁴, Frédéric Blondel¹⁴, Eelco Frickel¹⁵, Peng Chen¹⁶, Zhiqiang Hu¹⁶, Ronan Boisard¹⁷, Kutay Yilmazlar¹⁸, Alessandro Croce¹⁸, Violette Harnois¹⁹, Lijun Zhang²⁰, Ye Li²⁰, Ander Aristondo²¹, Iñigo Mendikoa Alonso²¹, Simone Mancini²², Koen Boorsma²², Feike Savenije²², David Marten²³, Rodrigo Soto-Valle²³, Christian Schulz²⁴, Stefan Netzband²⁴, Alessandro Bianchini²⁵, Francesco Papi²⁵, Stefano Cioni²⁵, Pau Trubat²⁶, Daniel Alarcon²⁶, Climent Molins²⁶, Marion Cormier²⁷, Konstantin Brüker²⁷, Thorsten Lutz²⁷, Qing Xiao²⁸, Zhongsheng Deng²⁸, Florence Haudin²⁹, and Akhilesh Goveas³⁰ Roger Bergua et al.

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¹National Wind Technology Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
²Mechanical Engineering Department, Politecnico di Milano, Milano, 20156, Italy
³Laboratory of Fluid-Machines, Dipartimento di Energia, Politecnico di Milano, Milano, 20156, Italy
⁴Wind Department, Bureau Veritas, Paris, 92937, France
⁵Wind Turbine Technologies, Centro Nacional de Energías Renovables, Sarriguren, 31621, Spain
⁶Integrated Simulation Department, China General Certification Center, Beijing, 100013, China
⁷Research Institute, China State Shipbuilding Corporation, Chongqing, 401122, China
⁸Offshore Technology Department, DNV, Bristol, BS2 0PS, UK
⁹Department of Wind Energy, Technical University of Denmark, Lyngby, 2800, Denmark
¹⁰State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, 116024, China
¹¹Département Electrotechnique et Mécanique des Structures, Électricité de France, Paris, 91120, France
¹²Wind Energy Department, eureka!, Errigoiti, 48309, Spain
¹³Department of Wind Energy, Institute for Energy Technology, Kjeller, NO-2027, Norway
¹⁴Offshore Wind and Ocean Energies, Institut Français du Pétrole Energies Nouvelles, Paris, 92852, France
¹⁵Research and Development, Maritime Research Institute Netherlands, Wageningen, 6708, The Netherlands
¹⁶Marine, Offshore and Subsea Technology Group, Newcastle University, Newcastle, NE1 7RU, UK
¹⁷Aerodynamic Department, Office National d’Etudes et de Recherches Aérospatiales, Paris, 92190, France
¹⁸Deptartment of Aerospace Science and Technology, Politecnico di Milano, Milano, 20156, Italy
¹⁹Floating Offshore Group, PRINCIPIA, La Ciotat, 13600, France
²⁰Wind Energy Group, Shanghai Jiao Tong University, Shanghai, 200240, China
²¹Department of Offshore Renewable Energy, Tecnalia Research & Innovation, Donostia-San Sebastián, 20009, Spain
²²Wind Energy Department, Netherlands Organisation for Applied Scientific Research, Petten, 1755, The Netherlands
²³Wind Energy Department, Technische Universität Berlin, Berlin, 10623, Germany
²⁴Fluid Dynamics and Ship Theory, Hamburg University of Technology, Hamburg, 21073, Germany
²⁵Department of Industrial Engineering, University of Florence, Florence, 50139, Italy
²⁶Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
²⁷Wind Energy Research Group, University of Stuttgart, Stuttgart, 70569, Germany
²⁸Department of Naval Architecture, Ocean and Marine Engineering, University of Strathclyde, Glasgow, G4 0LZ, UK
²⁹Research and Development Department, Vulcain Engineering, Neuilly-sur-Seine, 92200, France
³⁰Department of Load Engineering, WyndTek, Delft, 2628, The Netherlands

¹National Wind Technology Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
²Mechanical Engineering Department, Politecnico di Milano, Milano, 20156, Italy
³Laboratory of Fluid-Machines, Dipartimento di Energia, Politecnico di Milano, Milano, 20156, Italy
⁴Wind Department, Bureau Veritas, Paris, 92937, France
⁵Wind Turbine Technologies, Centro Nacional de Energías Renovables, Sarriguren, 31621, Spain
⁶Integrated Simulation Department, China General Certification Center, Beijing, 100013, China
⁷Research Institute, China State Shipbuilding Corporation, Chongqing, 401122, China
⁸Offshore Technology Department, DNV, Bristol, BS2 0PS, UK
⁹Department of Wind Energy, Technical University of Denmark, Lyngby, 2800, Denmark
¹⁰State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, 116024, China
¹¹Département Electrotechnique et Mécanique des Structures, Électricité de France, Paris, 91120, France
¹²Wind Energy Department, eureka!, Errigoiti, 48309, Spain
¹³Department of Wind Energy, Institute for Energy Technology, Kjeller, NO-2027, Norway
¹⁴Offshore Wind and Ocean Energies, Institut Français du Pétrole Energies Nouvelles, Paris, 92852, France
¹⁵Research and Development, Maritime Research Institute Netherlands, Wageningen, 6708, The Netherlands
¹⁶Marine, Offshore and Subsea Technology Group, Newcastle University, Newcastle, NE1 7RU, UK
¹⁷Aerodynamic Department, Office National d’Etudes et de Recherches Aérospatiales, Paris, 92190, France
¹⁸Deptartment of Aerospace Science and Technology, Politecnico di Milano, Milano, 20156, Italy
¹⁹Floating Offshore Group, PRINCIPIA, La Ciotat, 13600, France
²⁰Wind Energy Group, Shanghai Jiao Tong University, Shanghai, 200240, China
²¹Department of Offshore Renewable Energy, Tecnalia Research & Innovation, Donostia-San Sebastián, 20009, Spain
²²Wind Energy Department, Netherlands Organisation for Applied Scientific Research, Petten, 1755, The Netherlands
²³Wind Energy Department, Technische Universität Berlin, Berlin, 10623, Germany
²⁴Fluid Dynamics and Ship Theory, Hamburg University of Technology, Hamburg, 21073, Germany
²⁵Department of Industrial Engineering, University of Florence, Florence, 50139, Italy
²⁶Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
²⁷Wind Energy Research Group, University of Stuttgart, Stuttgart, 70569, Germany
²⁸Department of Naval Architecture, Ocean and Marine Engineering, University of Strathclyde, Glasgow, G4 0LZ, UK
²⁹Research and Development Department, Vulcain Engineering, Neuilly-sur-Seine, 92200, France
³⁰Department of Load Engineering, WyndTek, Delft, 2628, The Netherlands

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Received: 12 Aug 2022 – Discussion started: 23 Aug 2022

Abstract. This paper provides a summary of the work done within Phase III of the Offshore Code Comparison, Collaboration, Continued, with Correlation and unCertainty project (OC6), under International Energy Agency Wind Task 30. This phase focused on validating the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating support structure. Numerical models of the Danish Technical University 10-MW reference wind turbine were validated using measurement data from a 1:75 scale test performed during the UNsteady Aerodynamics for FLOating Wind (UNAFLOW) project and a follow-on experimental campaign, both performed at the Politecnico di Milano wind tunnel. Validation of the models was performed by comparing the loads for steady (fixed platform) and unsteady wind conditions (harmonic motion of the platform). For the unsteady wind conditions, the platform was forced to oscillate in the surge and pitch directions under several frequencies and amplitudes. These oscillations result in a wind variation that impacts the rotor loads (e.g., thrust and torque). For the conditions studied in these tests, the system mainly described a quasi-steady aerodynamic behavior. Only a small hysteresis in airfoil performance undergoing angle of attack variations in attached flow was observed. During the experiments, the rotor speed and blade pitch angle were held constant. However, in real wind turbine operating conditions, the surge and pitch variations would result in rotor speed variations and/or blade pitch actuations depending on the wind turbine controller region that the system is operating. Additional simulations with these control parameters were conducted to verify the fidelity between different models. Participant results showed in general a good agreement with the experimental measurements and the need to account for dynamic inflow when there are changes in the flow conditions due to the rotor speed variations or blade pitch actuations in response to surge and pitch motion. Numerical models not accounting for dynamic inflow effects predicted rotor loads that were 9 % lower in amplitude during rotor speed variations and 18 % higher in amplitude during blade pitch actuations.

How to cite. Bergua, R., Robertson, A., Jonkman, J., Branlard, E., Fontanella, A., Belloli, M., Schito, P., Zasso, A., Persico, G., Sanvito, A., Amet, E., Brun, C., Campaña-Alonso, G., Martín-San-Román, R., Cai, R., Cai, J., Qian, Q., Maoshi, W., Beardsell, A., Pirrung, G., Ramos-García, N., Shi, W., Fu, J., Corniglion, R., Lovera, A., Galván, J., Nygaard, T. A., dos Santos, C. R., Gilbert, P., Joulin, P.-A., Blondel, F., Frickel, E., Chen, P., Hu, Z., Boisard, R., Yilmazlar, K., Croce, A., Harnois, V., Zhang, L., Li, Y., Aristondo, A., Mendikoa Alonso, I., Mancini, S., Boorsma, K., Savenije, F., Marten, D., Soto-Valle, R., Schulz, C., Netzband, S., Bianchini, A., Papi, F., Cioni, S., Trubat, P., Alarcon, D., Molins, C., Cormier, M., Brüker, K., Lutz, T., Xiao, Q., Deng, Z., Haudin, F., and Goveas, A.: OC6 Project Phase III: Validation of the Aerodynamic Loading on a Wind Turbine Rotor Undergoing Large Motion Caused by a Floating Support Structure, Wind Energ. Sci. Discuss. [preprint], https://doi.org/10.5194/wes-2022-74, in review, 2022.

Roger Bergua et al.

Status: final response (author comments only)

RC1:
'Comment on wes-2022-74', Anonymous Referee #1, 19 Oct 2022

This reviewer finds the manuscript to be of high technical value, well organized, and enjoyable to read. The methods employed in understanding the relative strengths and weaknesses of various wind turbine aerodynamic modeling approaches, particularly for floating wind turbine applications, are sound. The results provided are comprehensive and cover a wide range and large quantity of possible numerical modeling approaches. The discussions surrounding the results are insightful, and the conclusions provide useful information for future offshore wind turbine designers and modelers (i.e., undsteady aerodynamic models will be required for cases employing realistic generator and blade pitch controls). This reviewer only found a few minor technical issues which can be easily remedied with a proofread (e.g., line 157 should probably read 'However, in reality it takes time...', line 159 should likely read '...(also referred to as dynamic wake)..., etc.).

Citation: https://doi.org/10.5194/wes-2022-74-RC1
- AC1: 'Reply on RC1', Roger Bergua Archeli, 21 Nov 2022
  
  We would like to thank Referee #1 for taking the necessary time to review the manuscript and for the kind words.
  We have examined our text carefully to find and correct typographical errors and mistakes in grammar, style, and spelling. We are going to upload a new manuscript with these changes addressed.
  
  Citation: https://doi.org/10.5194/wes-2022-74-AC1
RC2:
'Comment on wes-2022-74', Vasilis A. Riziotis, 25 Oct 2022

The paper presents the results of the benchmark exercise OC6 Phase III. The main focus of this joint venture is to compare predictions of aerodynamic models of varying fidelity among each other but also against wind tunnel measured datasets, for a rotor undergoing surge and pitching motion, that emulates wave induced motions of a FOWT.

The work presented in the paper constitutes a huge effort, both in terms of computational and human resources. The overall agreement of several models of varying fidelity is remarkable in many of the addressed conditions while differences, wherever they are observed, are plausible given the range of fidelity and the underlying assumptions in the different models. This agreement also implies a substantial effort by the coordinator of the task, to bridge the uncertainties due to inevitable misinterpretations of numerical and physical parameters that always occur in such extended benchmark exercises. Furthermore the knowledge gained by this exercise will be definitely valuable to the scientific community of rotor aerodynamicists and floating offshore technology.

Given the above, I believe that the paper is suitable for publication in WES journal. However, I would recommend the authors to revise their document, taking into account all my comments in the accompanying pdf. The most important ones are summarized below:

1) The authors state in page 7 line 161 “In GDW dynamic inflow is explicitly calculated through the use of an apparent mass in the induction calculation”. Traditionally, apparent mass in aerodynamics is the unsteady part of the pressure loads and it is not connected to hysteresis due to time varying wake induction (which is what GDW does). I would describe GDW as a semi-analytical frozen wake variant of a vortex wake model.

2) FVW models are further categorized to lifting line, lifting surface and 3D panel. Not all of them use pre-calculated polars and this is an important distinction that should be incorporated in table 4.

3) In asymmetric flow conditions, 2P, 4P etc. harmonics appear in the loads of the blade rotating frame (system attached to the rotating blade) which become 3P, 6P etc. when transferred to the tower frame. These are not only due to tower shadow. So, by low pass filtering you may omit part of the aerodynamic unsteady response. A band stop filter would be preferable in this case. Unless you are sure that loads are described by a pure 1P response which I doubt in the case of CFD or FWM. Or of course, if you are only interested in resolving the dynamic inflow effects due to the low frequency platform motion. In this case a proper explanation is required though.

4) I would recommend the authors to remove the FWM results for the wake inflection point from figure 9. The answer why these results are pointless can be found in the explanation by the authors. It is also necessary to provide more information on how much is the ambient turbulence in the wind tunnel test data and how this is simulated by the CFD tools.

5) There are several small syntax and grammar errors which however do not interfere with the understanding of the material. I corrected as many as I could in the accompanying pdf but I’m quite convinced that I missed many. Therefore I would recommend the authors to proof read the text before resubmitting it.

Citation: https://doi.org/10.5194/wes-2022-74-RC2
- AC2: 'Reply on RC2', Roger Bergua Archeli, 17 Jan 2023
  
  Reply with supporting material is provided in the attached PDF document.
  
  Citation: https://doi.org/10.5194/wes-2022-74-AC2

Roger Bergua et al.

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Short summary

The work examines if the motion experienced by an offshore floating wind turbine can significantly affect the rotor performance. It was observed that the system motion results in variations in the load, but these variations are not critical and the current simulation tools capture the physics properly. Interestingly, variations in the rotor speed or the blade pitch angle can have a larger impact than the system motion itself.


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