Articles | Volume 10, issue 1
https://doi.org/10.5194/wes-10-315-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wes-10-315-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
30 Jan 2025
Research article |
| 30 Jan 2025
| 30 Jan 2025
Drop-size-dependent effects in leading-edge rain erosion and their impact on erosion-safe mode operation
Nils Barfknecht
CORRESPONDING AUTHOR
Wind Energy Group, Faculty of Aerospace Engineering, Delft University of Technology, Delft, the Netherlands
Dominic von Terzi
Wind Energy Group, Faculty of Aerospace Engineering, Delft University of Technology, Delft, the Netherlands
Related authors
Nils Barfknecht and Dominic von Terzi
Wind Energ. Sci., 9, 2333–2357, https://doi.org/10.5194/wes-9-2333-2024, https://doi.org/10.5194/wes-9-2333-2024, 2024
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Rain droplets damage wind turbine blades due to the high impact speed at the tip. In this study, it is found that rain droplets and wind turbine blades interact aerodynamically. The rain droplets slow down and deform close to the blade. A model from another field of study was adapted and validated to study this process in detail. This effect reduced the predicted erosion damage by up to 50 %, primarily affecting smaller drops. It is shown how the slowdown effect can influence erosion mitigation.
Maria Cristina Vitulano, Delphine De Tavernier, Giuliano De Stefano, and Dominic von Terzi
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2025-125, https://doi.org/10.5194/wes-2025-125, 2025
Preprint under review for WES
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Wind turbines are increasing in size, pushing blade tips to operate at high speed. This study employs URANS simulations to investigate the unsteady aerodynamic response of a wind turbine airfoil to angle-of-attack changes across the transonic flow threshold. By varying reduced frequency and inflow Mach number, the analysis reveals the impact of compressibility on aerodynamic performance, including a hysteresis effect, which highlights its importance for the design of next-generation rotors.
Simone Chellini, Delphine De Tavernier, and Dominic von Terzi
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2025-121, https://doi.org/10.5194/wes-2025-121, 2025
Preprint under review for WES
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Growing interest in high-velocity physics is justifying research in new experimental aerodynamics. Our work provides the knowledge foundations for the next generation of large wind turbine rotors. We highlight airfoil-dependent structures and forces found in a large-scale wind tunnel experiment, for which different trends are observed. Importantly, the results delve into the force enhancement due to dynamic angle of attack oscillation, leading to higher aerodynamic loads for the blade.
Abhyuday Aditya, Delphine De Tavernier, Ferdinand Schrijer, Bas van Oudheusden, and Dominic von Terzi
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2025-65, https://doi.org/10.5194/wes-2025-65, 2025
Preprint under review for WES
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This study is the first to experimentally test how wind turbine blades behave at near-supersonic speeds, a condition expected in the largest turbines. In the experiments, we observed unstable and potentially detrimental shock waves that become stronger at higher speeds and angles. Basic prediction tools in wind turbine design miss these details, highlighting the need for better tools and experiments to understand the extreme conditions faced by modern wind turbines.
Rishikesh Joshi, Dominic von Terzi, and Roland Schmehl
Wind Energ. Sci., 10, 695–718, https://doi.org/10.5194/wes-10-695-2025, https://doi.org/10.5194/wes-10-695-2025, 2025
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This paper presents a methodology for assessing the system design and scaling trends in airborne wind energy (AWE). A multi-disciplinary design, analysis, and optimisation (MDAO) framework was developed, integrating power, energy production, and cost models for the fixed-wing ground-generation (GG) AWE concept. Using the levelized cost of electricity (LCoE) as the design objective, we found that the optimal size of systems lies between the rated power of 100 and 1000 kW.
Ricardo Amaral, Felix Houtin-Mongrolle, Dominic von Terzi, Kasper Laugesen, Paul Deglaire, and Axelle Viré
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2025-34, https://doi.org/10.5194/wes-2025-34, 2025
Manuscript not accepted for further review
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This work uses simulations to investigate floating offshore wind turbines which have the potential to supply the world's electricity demand many times by 2040. In particular, the effect of the rotor motion on the wake was investigated by forcing the turbine to move under different motions and the results highlight differences between motions. While some motions led to a wake behavior that was close to that of a fixed-bottom turbine, other motions produced a remarkably different wake structure.
Maria Cristina Vitulano, Delphine De Tavernier, Giuliano De Stefano, and Dominic von Terzi
Wind Energ. Sci., 10, 103–116, https://doi.org/10.5194/wes-10-103-2025, https://doi.org/10.5194/wes-10-103-2025, 2025
Short summary
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Next-generation wind turbines are the largest rotating machines ever built, experiencing local flow Mach where the incompressibility assumption is violated, and even transonic flow can occur. This study assesses the transonic features over the FFA-W3-211 wind turbine tip airfoil for selected industrial test cases, defines the subsonic–supersonic flow threshold and evaluates the Reynolds number effects on transonic flow occurrence. Shock wave occurrence is also depicted.
Nils Barfknecht and Dominic von Terzi
Wind Energ. Sci., 9, 2333–2357, https://doi.org/10.5194/wes-9-2333-2024, https://doi.org/10.5194/wes-9-2333-2024, 2024
Short summary
Short summary
Rain droplets damage wind turbine blades due to the high impact speed at the tip. In this study, it is found that rain droplets and wind turbine blades interact aerodynamically. The rain droplets slow down and deform close to the blade. A model from another field of study was adapted and validated to study this process in detail. This effect reduced the predicted erosion damage by up to 50 %, primarily affecting smaller drops. It is shown how the slowdown effect can influence erosion mitigation.
Mihir Kishore Mehta, Michiel Zaaijer, and Dominic von Terzi
Wind Energ. Sci., 9, 2283–2300, https://doi.org/10.5194/wes-9-2283-2024, https://doi.org/10.5194/wes-9-2283-2024, 2024
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In a subsidy-free era, there is a need to optimize wind turbines for maximizing farm revenue instead of minimizing cost of energy. A wind-farm-level modeling framework with a simplified market model is used to optimize the turbine size for maximum profitability. The results show that the optimum size is driven mainly by the choice of the economic metric and the market price scenario, with a design optimized for the cost of energy already performing well w.r.t. most profitability-based metrics
Shyam VimalKumar, Delphine De Tavernier, Dominic von Terzi, Marco Belloli, and Axelle Viré
Wind Energ. Sci., 9, 1967–1983, https://doi.org/10.5194/wes-9-1967-2024, https://doi.org/10.5194/wes-9-1967-2024, 2024
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When standing still without a nacelle or blades, the vibrations on a wind turbine tower are of concern to its structural health. This study finds that the air which flows around the tower recirculates behind the tower, forming so-called wakes. These wakes initiate the vibration, and the movement itself causes the vibration to increase or decrease depending on the wind speed. The current study uses a methodology called force partitioning to analyse this in depth.
Mihir Mehta, Michiel Zaaijer, and Dominic von Terzi
Wind Energ. Sci., 9, 141–163, https://doi.org/10.5194/wes-9-141-2024, https://doi.org/10.5194/wes-9-141-2024, 2024
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Turbines are becoming larger. However, it is important to understand the key drivers of turbine design and explore the possibility of a global optimum, beyond which further upscaling might not reduce the cost of energy. This study explores, for a typical farm, the entire turbine design space with respect to rated power and rotor diameter. The results show a global optimum that is subject to various modeling uncertainties, farm design conditions, and policies with respect to wind farm tendering.
Related subject area
Thematic area: Fluid mechanics | Topic: Wind turbine aerodynamics
Modeling the influence of streamwise flow field acceleration on the aerodynamic performance of an actuator disk
A scaling methodology for the Hybrid-Lambda Rotor – characterization and validation in wind tunnel experiments
On the influence of cross-sectional deformations on the aerodynamic performance of wind turbine rotor blades
Validation of the near-wake of a scaled X-Rotor vertical-axis wind turbine predicted by a free-wake vortex model
Disentangling wake and projection effects in the aerodynamics of wind turbines with curved blades
Glauert's optimum rotor disk revisited – a calculus of variations solution and exact integrals for thrust and bending moment coefficients
On the wake re-energization of the X-Rotor vertical-axis wind turbine via the vortex-generator strategy
Characterization of dynamic stall of a wind turbine airfoil with a high Reynolds number
Numerical analysis of transonic flow over the FFA-W3-211 wind turbine tip airfoil
How does turbulence affect wake development in floating wind turbines? A critical assessment
Characterization of vortex-shedding regimes and lock-in response of a wind turbine airfoil with two high-fidelity simulation approaches
Aerodynamic interaction of rain and wind turbine blades: the significance of droplet slowdown and deformation for leading-edge erosion
Force-partitioning analysis of vortex-induced vibrations of wind turbine tower sections
Near wake behavior of an asymmetric wind turbine rotor
Investigation of blade flexibility effects on the loads and wake of a 15 MW wind turbine using a flexible actuator line method
On optimizing the sensor spacing for pressure measurements on wind turbine airfoils
Experimental analysis of a horizontal-axis wind turbine with swept blades using PIV data
Aerodynamic characterisation of a thrust-scaled IEA 15 MW wind turbine model: experimental insights using PIV data
Going beyond BEM with BEM: an insight into dynamic inflow effects on floating wind turbines
Quantifying the impact of modeling fidelity on different substructure concepts – Part 2: Code-to-code comparison in realistic environmental conditions
Wind turbine rotors in surge motion: new insights into unsteady aerodynamics of floating offshore wind turbines (FOWTs) from experiments and simulations
An insight into the capability of the actuator line method to resolve tip vortices
Aerodynamic model comparison for an X-shaped vertical-axis wind turbine
Development and application of a mesh generator intended for unsteady vortex-lattice method simulations of wind turbines and wind farms
An experimental study on the aerodynamic loads of a floating offshore wind turbine under imposed motions
Developing a digital twin framework for wind tunnel testing: validation of turbulent inflow and airfoil load applications
Influence of rotor blade flexibility on the near-wake behavior of the NREL 5 MW wind turbine
Field-data-based validation of an aero-servo-elastic solver for high-fidelity large-eddy simulations of industrial wind turbines
An analytical linear two-dimensional actuator disc model and comparisons with computational fluid dynamics (CFD) simulations
On the characteristics of the wake of a wind turbine undergoing large motions caused by a floating structure: an insight based on experiments and multi-fidelity simulations from the OC6 project Phase III
Forced-motion simulations of vortex-induced vibrations of wind turbine blades – a study of sensitivities
Towards smart blades for vertical axis wind turbines: different airfoil shapes and tip speed ratios
Numerical study of the unsteady blade root aerodynamics of a 2 MW wind turbine equipped with vortex generators
Generalized analytical body force model for actuator disc computations of wind turbines
Nonlinear inviscid aerodynamics of a wind turbine rotor in surge, sway, and yaw motions using a free-wake panel method
OC6 project Phase III: validation of the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating support structure
A simple vortex model applied to an idealized rotor in sheared inflow
Comparison of free vortex wake and blade element momentum results against large-eddy simulation results for highly flexible turbines under challenging inflow conditions
Numerical simulations of ice accretion on wind turbine blades: are performance losses due to ice shape or surface roughness?
Progress in the validation of rotor aerodynamic codes using field data
A comparison of dynamic inflow models for the blade element momentum method
Multiple limit cycle amplitudes in high-fidelity predictions of standstill wind turbine blade vibrations
Model tests of a 10 MW semi-submersible floating wind turbine under waves and wind using hybrid method to integrate the rotor thrust and moments
Atmospheric rotating rig testing of a swept blade tip and comparison with multi-fidelity aeroelastic simulations
A WaveNet-based fully stochastic dynamic stall model
Experimental analysis of the dynamic inflow effect due to coherent gusts
High-Reynolds-number wind turbine blade equipped with root spoilers – Part 2: Impact on energy production and turbine lifetime
Wind tunnel investigation of the aerodynamic response of two 15 MW floating wind turbines
Vertical wake deflection for floating wind turbines by differential ballast control
High-fidelity aeroelastic analyses of wind turbines in complex terrain: fluid–structure interaction and aerodynamic modeling
Clemens Paul Zengler, Niels Troldborg, and Mac Gaunaa
Wind Energ. Sci., 10, 1485–1497, https://doi.org/10.5194/wes-10-1485-2025, https://doi.org/10.5194/wes-10-1485-2025, 2025
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Wind turbine power performance is mostly calculated based on the wind speed measured at the turbine position. The presented results imply that it is necessary to also assess how the undisturbed wind speed changes in the flow direction to accurately predict the power performance. In other words, the acceleration of the flow is relevant for the energy production. An outcome of this work is a simple model that can be used to include flow acceleration in power performance predictions.
Daniel Ribnitzky, Vlaho Petrović, and Martin Kühn
Wind Energ. Sci., 10, 1329–1349, https://doi.org/10.5194/wes-10-1329-2025, https://doi.org/10.5194/wes-10-1329-2025, 2025
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In this paper, the Hybrid-Lambda Rotor is scaled to wind tunnel size and validated in wind tunnel experiments. The objectives are to derive a scaling methodology, to investigate the influence of the steep gradients of axial induction along the blade span, and to characterize the near wake. The study reveals complex three-dimensional flow patterns for blade designs with non-uniform loading, and it can offer new inspirations when solving other scaling problems for complex wind turbine systems.
Julia Gebauer, Felix Prigge, Dominik Ahrens, Lars Wein, and Claudio Balzani
Wind Energ. Sci., 10, 679–694, https://doi.org/10.5194/wes-10-679-2025, https://doi.org/10.5194/wes-10-679-2025, 2025
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The amount of energy that can be extracted from wind depends primarily on the blade geometry, which can be affected by elastic deformations. This paper presents a first study analysing the influence of cross-sectional deformations of a 15 MW wind turbine blade on aero-elastic simulations. The results show that cross-sectional deformations have a minor influence on the internal loads of rotor blades in normal operation.
Adhyanth Giri Ajay, David Bensason, and Delphine De Tavernier
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2025-54, https://doi.org/10.5194/wes-2025-54, 2025
Revised manuscript accepted for WES
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We studied the airflow around a new type of wind turbine called the X-Rotor, which could help reduce the cost of offshore wind energy. Comparing a computer simulation model and wind tunnel experiments, we found that the model correlates well under normal conditions but becomes less accurate when the blades turn. Our results show that future designs of this turbine category must consider complex three-dimensional flow effects to better predict and improve wind turbine performance.
Ang Li, Mac Gaunaa, Georg Raimund Pirrung, and Kenneth Lønbæk
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2025-30, https://doi.org/10.5194/wes-2025-30, 2025
Revised manuscript accepted for WES
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This study improves the analysis of curved wind turbine blades, such as those with sweep or prebend. Existing methods often blend different effects on blade performance, making design optimization challenging. We developed a framework that disentangles these effects, providing clearer insights. Our findings show that the aerodynamic influences of sweep and prebend can be modeled separately and combined, simplifying modeling processes and supporting more efficient blade design.
Divya Tyagi and Sven Schmitz
Wind Energ. Sci., 10, 451–460, https://doi.org/10.5194/wes-10-451-2025, https://doi.org/10.5194/wes-10-451-2025, 2025
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This paper adds to the literature on rotor disk theory by solving a century-old problem with a different mathematical approach. The classical results are recovered, while also adding expressions and asymptotic limits for performance coefficients that were not included in the original theory. This work adds to classical rotor disk theory as a valuable contribution to research and teaching in wind turbine aerodynamics.
David Bensason, Andrea Sciacchitano, and Carlos Ferreira
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2025-3, https://doi.org/10.5194/wes-2025-3, 2025
Revised manuscript accepted for WES
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This study experimentally explores the wake of the novel X-Rotor vertical axis wind turbine. Passive blade pitch is used to favorably modify the wake topology and subsequent energy replenishment process. The results demonstrate significant increases in available power for downstream rotors and the underlying mechanisms, highlighting the potential of vertical-axis wind turbines and passive blade pitch control for high-energy-density wind farm applications.
Hye Rim Kim, Jasson A. Printezis, Jan Dominik Ahrens, Joerg R. Seume, and Lars Wein
Wind Energ. Sci., 10, 161–175, https://doi.org/10.5194/wes-10-161-2025, https://doi.org/10.5194/wes-10-161-2025, 2025
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The need for renewable energy, thus more efficient wind turbines, is ever increasing. Accurate prediction of the performance in the design stage is necessary. In particular, predicting the dynamic performance of a wind turbine in the region where it undergoes highly unsteady flow is very challenging. We investigated the dynamic performance of an airfoil, which is typical for megastructure wind farms, in support of the development of more efficient design tools in the future.
Maria Cristina Vitulano, Delphine De Tavernier, Giuliano De Stefano, and Dominic von Terzi
Wind Energ. Sci., 10, 103–116, https://doi.org/10.5194/wes-10-103-2025, https://doi.org/10.5194/wes-10-103-2025, 2025
Short summary
Short summary
Next-generation wind turbines are the largest rotating machines ever built, experiencing local flow Mach where the incompressibility assumption is violated, and even transonic flow can occur. This study assesses the transonic features over the FFA-W3-211 wind turbine tip airfoil for selected industrial test cases, defines the subsonic–supersonic flow threshold and evaluates the Reynolds number effects on transonic flow occurrence. Shock wave occurrence is also depicted.
Leonardo Pagamonci, Francesco Papi, Gabriel Cojocaru, Marco Belloli, and Alessandro Bianchini
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2024-169, https://doi.org/10.5194/wes-2024-169, 2025
Revised manuscript accepted for WES
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The study presents a critical analysis, using wind tunnel experiments and LES CFD simulations, aimed at quantifying to what extent turbulence affects the wake structures of a floating turbine undergoing large motions. Analyses show that, whenever realistic turbulence comes to play, only small gains in terms of wake recovery are noticed in FOWTs in comparison to bottom-fixed turbines, suggesting the absence of hypothesized superposition effects between inflow and platform motion.
Ricardo Fernandez-Aldama, George Papadakis, Oscar Lopez-Garcia, Sergio Avila-Sanchez, Vasilis A. Riziotis, Alvaro Cuerva-Tejero, and Cristobal Gallego-Castillo
Wind Energ. Sci., 10, 17–39, https://doi.org/10.5194/wes-10-17-2025, https://doi.org/10.5194/wes-10-17-2025, 2025
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As longer wind turbine blades are designed, concern about vortex-induced vibration (VIV) grows. This study identifies a new intermittent vortex-shedding behaviour through a long-time simulation of a 3D wind turbine airfoil. This finding motivates a novel evaluation of airfoil vibrations at different inflow velocities. Our results show that both 2D and 3D simulations predict similar VIV characteristics during large motions, enhancing our understanding and prediction of VIV in turbine blades.
Nils Barfknecht and Dominic von Terzi
Wind Energ. Sci., 9, 2333–2357, https://doi.org/10.5194/wes-9-2333-2024, https://doi.org/10.5194/wes-9-2333-2024, 2024
Short summary
Short summary
Rain droplets damage wind turbine blades due to the high impact speed at the tip. In this study, it is found that rain droplets and wind turbine blades interact aerodynamically. The rain droplets slow down and deform close to the blade. A model from another field of study was adapted and validated to study this process in detail. This effect reduced the predicted erosion damage by up to 50 %, primarily affecting smaller drops. It is shown how the slowdown effect can influence erosion mitigation.
Shyam VimalKumar, Delphine De Tavernier, Dominic von Terzi, Marco Belloli, and Axelle Viré
Wind Energ. Sci., 9, 1967–1983, https://doi.org/10.5194/wes-9-1967-2024, https://doi.org/10.5194/wes-9-1967-2024, 2024
Short summary
Short summary
When standing still without a nacelle or blades, the vibrations on a wind turbine tower are of concern to its structural health. This study finds that the air which flows around the tower recirculates behind the tower, forming so-called wakes. These wakes initiate the vibration, and the movement itself causes the vibration to increase or decrease depending on the wind speed. The current study uses a methodology called force partitioning to analyse this in depth.
Pin Chun Yen, Wei Yu, and Fulvio Scarano
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2024-122, https://doi.org/10.5194/wes-2024-122, 2024
Revised manuscript accepted for WES
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This study explores how changing wind turbine blade length affects airflow behind the turbine. Using high- and low-fidelity simulations, we found that varying blade lengths accelerate wake interactions but don’t improve flow recovery or energy capture. Turbulence plays a bigger role in breaking up airflow patterns than rotor asymmetry. These findings provide insights for designing more efficient wind turbines.
Francois Trigaux, Philippe Chatelain, and Grégoire Winckelmans
Wind Energ. Sci., 9, 1765–1789, https://doi.org/10.5194/wes-9-1765-2024, https://doi.org/10.5194/wes-9-1765-2024, 2024
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In this research, the impact of blade flexibility is investigated for a very large wind turbine using numerical simulations. It is shown that bending and torsion decrease the power production and affect aerodynamic loads. Blade deformation also affects the flow of wind behind the turbine, resulting in a higher mean velocity. Our study highlights the importance of including blade flexibility in the simulation of large wind turbines to obtain accurate power and load predictions.
Erik K. Fritz, Christopher L. Kelley, and Kenneth A. Brown
Wind Energ. Sci., 9, 1713–1726, https://doi.org/10.5194/wes-9-1713-2024, https://doi.org/10.5194/wes-9-1713-2024, 2024
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This study investigates the benefits of optimizing the spacing of pressure sensors for measurement campaigns on wind turbine blades and airfoils. It is demonstrated that local aerodynamic properties can be estimated considerably more accurately when the sensor layout is optimized compared to commonly used simpler sensor layouts. This has the potential to reduce the number of sensors without losing measurement accuracy and, thus, reduce the instrumentation complexity and experiment cost.
Erik Fritz, Koen Boorsma, and Carlos Ferreira
Wind Energ. Sci., 9, 1617–1629, https://doi.org/10.5194/wes-9-1617-2024, https://doi.org/10.5194/wes-9-1617-2024, 2024
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This study presents results from a wind tunnel experiment on a model wind turbine with swept blades, thus blades curved in the rotor plane. Using a non-intrusive measurement technique, the flow around the turbine blades was measured from which blade-level aerodynamics are derived in post-processing. The detailed experimental database gives insight into swept-blade aerodynamics and has great value in validating numerical tools, which aim at simulating swept wind turbine blades.
Erik Fritz, André Ribeiro, Koen Boorsma, and Carlos Ferreira
Wind Energ. Sci., 9, 1173–1187, https://doi.org/10.5194/wes-9-1173-2024, https://doi.org/10.5194/wes-9-1173-2024, 2024
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This study presents results from a wind tunnel experiment on a model wind turbine. Using a non-intrusive measurement technique, the flow around the turbine blades was measured. In post-processing, the blade-level aerodynamics are derived from the measured flow fields. The detailed experimental database has great value in validating numerical tools of varying complexity, which aim at simulating wind turbine aerodynamics as accurately as possible.
Francesco Papi, Jason Jonkman, Amy Robertson, and Alessandro Bianchini
Wind Energ. Sci., 9, 1069–1088, https://doi.org/10.5194/wes-9-1069-2024, https://doi.org/10.5194/wes-9-1069-2024, 2024
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Blade element momentum (BEM) theory is the backbone of many industry-standard aerodynamic models. However, the analysis of floating offshore wind turbines (FOWTs) introduces new challenges, which could put BEM models to the test. This study systematically compares four aerodynamic models, ranging from BEM to computational fluid dynamics, in an attempt to shed light on the unsteady aerodynamic phenomena that are at stake in FOWTs and whether BEM is able to model them appropriately.
Francesco Papi, Giancarlo Troise, Robert Behrens de Luna, Joseph Saverin, Sebastian Perez-Becker, David Marten, Marie-Laure Ducasse, and Alessandro Bianchini
Wind Energ. Sci., 9, 981–1004, https://doi.org/10.5194/wes-9-981-2024, https://doi.org/10.5194/wes-9-981-2024, 2024
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Wind turbines need to be simulated for thousands of hours to estimate design loads. Mid-fidelity numerical models are typically used for this task to strike a balance between computational cost and accuracy. The considerable displacements of floating wind turbines may be a challenge for some of these models. This paper enhances comprehension of how modeling theories affect floating wind turbine loads by comparing three codes across three turbines, simulated in a real environment.
Christian W. Schulz, Stefan Netzband, Umut Özinan, Po Wen Cheng, and Moustafa Abdel-Maksoud
Wind Energ. Sci., 9, 665–695, https://doi.org/10.5194/wes-9-665-2024, https://doi.org/10.5194/wes-9-665-2024, 2024
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Understanding the underlying physical phenomena of the aerodynamics of floating offshore wind turbines (FOWTs) is crucial for successful simulations. No consensus has been reached in the research community on which unsteady aerodynamic phenomena are relevant and how much they can influence the loads acting on a FOWT. This work contributes to the understanding and characterisation of such unsteady phenomena using a novel experimental approach and comprehensive numerical investigations.
Pier Francesco Melani, Omar Sherif Mohamed, Stefano Cioni, Francesco Balduzzi, and Alessandro Bianchini
Wind Energ. Sci., 9, 601–622, https://doi.org/10.5194/wes-9-601-2024, https://doi.org/10.5194/wes-9-601-2024, 2024
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The actuator line method (ALM) is a powerful tool for wind turbine simulation but struggles to resolve tip effects. The reason is still unclear. To investigate this, we use advanced angle of attack sampling and vortex tracking techniques to analyze the flow around a NACA0018 finite wing, simulated with ALM and blade-resolved computational fluid dynamics. Results show that the ALM can account for tip effects if the correct angle of attack sampling and force projection strategies are adopted.
Adhyanth Giri Ajay, Laurence Morgan, Yan Wu, David Bretos, Aurelio Cascales, Oscar Pires, and Carlos Ferreira
Wind Energ. Sci., 9, 453–470, https://doi.org/10.5194/wes-9-453-2024, https://doi.org/10.5194/wes-9-453-2024, 2024
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This paper compares six different numerical models to predict the performance of an X-shaped vertical-axis wind turbine, offering insights into how it works in 3D when its blades are fixed at specific angles. The results showed the 3D models here reliably predict the performance while still taking this turbine's complex aerodynamics into account compared to 2D models. Further, these blade angles caused more complexity in predicting the turbine's behaviour, which is highlighted in this paper.
Bruno A. Roccia, Luis R. Ceballos, Marcos L. Verstraete, and Cristian G. Gebhardt
Wind Energ. Sci., 9, 385–416, https://doi.org/10.5194/wes-9-385-2024, https://doi.org/10.5194/wes-9-385-2024, 2024
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In the literature there is a lack of meshing tools when it comes to building aerodynamic grids of wind turbines/farms to be used along with potential flow solvers. In this work, we present a detailed description of the geometric modeling and computational implementation of an interactive mesh generator, named UVLMeshGen, for onshore/offshore wind farms. The work is completed by providing a series of aerodynamic results related to wind turbines/farms to show the capacity of the mesh generator.
Federico Taruffi, Felipe Novais, and Axelle Viré
Wind Energ. Sci., 9, 343–358, https://doi.org/10.5194/wes-9-343-2024, https://doi.org/10.5194/wes-9-343-2024, 2024
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Floating wind turbines are subject to complex aerodynamics that are not yet fully understood. Lab-scale experiments are crucial for capturing these phenomena and validate numerical tools. This paper presents a new wind tunnel experimental setup able to study the response of a wind turbine rotor when subjected to prescribed motions in 6 degrees of freedom. The observed unsteady effects underscore the importance of pursuing research on the impact of floater motions on wind turbine performance.
Rishabh Mishra, Emmanuel Guilmineau, Ingrid Neunaber, and Caroline Braud
Wind Energ. Sci., 9, 235–252, https://doi.org/10.5194/wes-9-235-2024, https://doi.org/10.5194/wes-9-235-2024, 2024
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To investigate the impact of turbulence on aerodynamic forces, we first model turbulent kinetic energy decay theoretically using the Taylor length scale and employ this model to create a digital wind tunnel replica for simulating grid-generated turbulence. Experimental validation shows good alignment among theory, simulations, and experiments, paving the way for aerodynamic simulations. Finally, we successfully use the digital replica to obtain force coefficients for a 2D rotor blade section.
Leo Höning, Laura J. Lukassen, Bernhard Stoevesandt, and Iván Herráez
Wind Energ. Sci., 9, 203–218, https://doi.org/10.5194/wes-9-203-2024, https://doi.org/10.5194/wes-9-203-2024, 2024
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This study analyzes the impact of wind turbine rotor blade flexibility on the aerodynamic loading of the blades and the consequential wind characteristics in the near wake of the turbine. It is shown that gravitation leads to rotational periodic fluctuations of blade loading, which directly impacts the trajectory of the blade tip vortex at different rotor blade positions while also resulting in a non-uniform wind velocity deficit in the wake of the wind turbine.
Etienne Muller, Simone Gremmo, Félix Houtin-Mongrolle, Bastien Duboc, and Pierre Bénard
Wind Energ. Sci., 9, 25–48, https://doi.org/10.5194/wes-9-25-2024, https://doi.org/10.5194/wes-9-25-2024, 2024
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This article presents an advanced tool designed for the high-fidelity and high-performance simulation of operating wind turbines, allowing for instance the computation of a blade deformation, as well as of the surrounding airflow. As this tool relies on coupling two existing codes, the coupling strategy is first described in depth. The article then compares the code results to field data for validation.
Helge Aagaard Madsen
Wind Energ. Sci., 8, 1853–1872, https://doi.org/10.5194/wes-8-1853-2023, https://doi.org/10.5194/wes-8-1853-2023, 2023
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We present a linear analytical solution for a two-dimensional (2-D) actuator disc (AD) for a plane disc, a yawed disc and a coned disc. Comparisons of the 2-D model with three-dimensional computational fluid dynamics (CFD) AD simulations for a circular yawed disc and with an axis-symmetric CFD simulation of a coned disc show good correlation for the normal velocity component of the disc. This indicates that the 2-D AD model could form the basis for a consistent, simple new rotor induction model.
Stefano Cioni, Francesco Papi, Leonardo Pagamonci, Alessandro Bianchini, Néstor Ramos-García, Georg Pirrung, Rémi Corniglion, Anaïs Lovera, Josean Galván, Ronan Boisard, Alessandro Fontanella, Paolo Schito, Alberto Zasso, Marco Belloli, Andrea Sanvito, Giacomo Persico, Lijun Zhang, Ye Li, Yarong Zhou, Simone Mancini, Koen Boorsma, Ricardo Amaral, Axelle Viré, Christian W. Schulz, Stefan Netzband, Rodrigo Soto-Valle, David Marten, Raquel Martín-San-Román, Pau Trubat, Climent Molins, Roger Bergua, Emmanuel Branlard, Jason Jonkman, and Amy Robertson
Wind Energ. Sci., 8, 1659–1691, https://doi.org/10.5194/wes-8-1659-2023, https://doi.org/10.5194/wes-8-1659-2023, 2023
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Simulations of different fidelities made by the participants of the OC6 project Phase III are compared to wind tunnel wake measurements on a floating wind turbine. Results in the near wake confirm that simulations and experiments tend to diverge from the expected linearized quasi-steady behavior when the reduced frequency exceeds 0.5. In the far wake, the impact of platform motion is overestimated by simulations and even seems to be oriented to the generation of a wake less prone to dissipation.
Christian Grinderslev, Felix Houtin-Mongrolle, Niels Nørmark Sørensen, Georg Raimund Pirrung, Pim Jacobs, Aqeel Ahmed, and Bastien Duboc
Wind Energ. Sci., 8, 1625–1638, https://doi.org/10.5194/wes-8-1625-2023, https://doi.org/10.5194/wes-8-1625-2023, 2023
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In standstill conditions wind turbines are at risk of vortex-induced vibrations (VIVs). VIVs can become large and lead to significant fatigue of the wind turbine structure over time. Thus it is important to have tools that can accurately compute this complex phenomenon. This paper studies the sensitivities to the chosen models of computational fluid dynamics (CFD) simulations when modelling VIVs and finds that much care is needed when setting up simulations, especially for specific flow angles.
Mohammad Rasoul Tirandaz, Abdolrahim Rezaeiha, and Daniel Micallef
Wind Energ. Sci., 8, 1403–1424, https://doi.org/10.5194/wes-8-1403-2023, https://doi.org/10.5194/wes-8-1403-2023, 2023
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Vertical axis wind turbines experience a variation of torque and power throughout their rotation. Traditional non-morphing blades are intrinsically not able to respond to this variation, resulting in a turbine which has suboptimal performance. In principle, it is possible to have a morphing blade that adapts to the blade's rotation and changes its geometry in such a way as to optimise the performance of the turbine. This paper addresses the question of how such blade should morph as it rotates.
Ferdinand Seel, Thorsten Lutz, and Ewald Krämer
Wind Energ. Sci., 8, 1369–1385, https://doi.org/10.5194/wes-8-1369-2023, https://doi.org/10.5194/wes-8-1369-2023, 2023
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Vortex generators are evaluated on a 2 MW wind turbine rotor blade by computational fluid dynamic methods. Those devices delay flow separation on the airfoils and thus increase their efficiency. On the wind turbine blade, rotational phenomena (e.g. rotational augmentation) appear and interact with the vortices from the vortex generators. The understanding of those interactions is crucial in order to optimise the placement of the vortex generators and evaluate their real efficiency on the blade.
Jens N. Sørensen
Wind Energ. Sci., 8, 1017–1027, https://doi.org/10.5194/wes-8-1017-2023, https://doi.org/10.5194/wes-8-1017-2023, 2023
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The paper presents a simple analytical model that, with surprisingly good accuracy, represents the loading for virtually any horizontal axis wind turbine, independent of size and operating regime. The aim of the model is to have a simple tool that may represent the loading of any wind turbine without having access to the details regarding the specific geometry and airfoil data, information that is normally kept confidential by the manufacturer of the turbine.
André F. P. Ribeiro, Damiano Casalino, and Carlos S. Ferreira
Wind Energ. Sci., 8, 661–675, https://doi.org/10.5194/wes-8-661-2023, https://doi.org/10.5194/wes-8-661-2023, 2023
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Floating offshore wind turbines move due to not having a rigid foundation. Hence, as the blades rotate they experience more complex aerodynamics than standard onshore wind turbines. In this paper, we show computational simulations of a wind turbine rotor moving in various ways and quantify the effects of the motion in the forces acting on the blades. We show that these forces behave in nonlinear ways in some cases.
Roger Bergua, Amy Robertson, Jason Jonkman, Emmanuel Branlard, Alessandro Fontanella, Marco Belloli, Paolo Schito, Alberto Zasso, Giacomo Persico, Andrea Sanvito, Ervin Amet, Cédric Brun, Guillén Campaña-Alonso, Raquel Martín-San-Román, Ruolin Cai, Jifeng Cai, Quan Qian, Wen Maoshi, Alec Beardsell, Georg Pirrung, Néstor Ramos-García, Wei Shi, Jie Fu, Rémi Corniglion, Anaïs Lovera, Josean Galván, Tor Anders Nygaard, Carlos Renan dos Santos, Philippe Gilbert, Pierre-Antoine Joulin, Frédéric Blondel, Eelco Frickel, Peng Chen, Zhiqiang Hu, Ronan Boisard, Kutay Yilmazlar, Alessandro Croce, Violette Harnois, Lijun Zhang, Ye Li, Ander Aristondo, Iñigo Mendikoa Alonso, Simone Mancini, Koen Boorsma, Feike Savenije, David Marten, Rodrigo Soto-Valle, Christian W. Schulz, Stefan Netzband, Alessandro Bianchini, Francesco Papi, Stefano Cioni, Pau Trubat, Daniel Alarcon, Climent Molins, Marion Cormier, Konstantin Brüker, Thorsten Lutz, Qing Xiao, Zhongsheng Deng, Florence Haudin, and Akhilesh Goveas
Wind Energ. Sci., 8, 465–485, https://doi.org/10.5194/wes-8-465-2023, https://doi.org/10.5194/wes-8-465-2023, 2023
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This 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.
Mac Gaunaa, Niels Troldborg, and Emmanuel Branlard
Wind Energ. Sci., 8, 503–513, https://doi.org/10.5194/wes-8-503-2023, https://doi.org/10.5194/wes-8-503-2023, 2023
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We present an analytical vortex model. Despite its simplicity, the model is fully consistent with 1D momentum theory. It shows that the flow through a non-uniformly loaded rotor operating in non-uniform inflow behaves locally as predicted by 1D momentum theory. As a consequence, the local power coefficient (based on local inflow) of an ideal rotor is unaltered by the presence of shear. Finally, the model shows that there is no cross-shear deflection of the wake of a rotor in sheared inflow.
Kelsey Shaler, Benjamin Anderson, Luis A. Martínez-Tossas, Emmanuel Branlard, and Nick Johnson
Wind Energ. Sci., 8, 383–399, https://doi.org/10.5194/wes-8-383-2023, https://doi.org/10.5194/wes-8-383-2023, 2023
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Free-vortex wake (OLAF) and low-fidelity blade-element momentum (BEM) structural results are compared to high-fidelity simulation results for a flexible downwind turbine for varying inflow conditions. Overall, OLAF results were more consistent than BEM results when compared to SOWFA results under challenging inflow conditions. Differences between OLAF and BEM results were dominated by yaw misalignment angle, with varying shear exponent and turbulence intensity causing more subtle differences.
Francesco Caccia and Alberto Guardone
Wind Energ. Sci., 8, 341–362, https://doi.org/10.5194/wes-8-341-2023, https://doi.org/10.5194/wes-8-341-2023, 2023
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Ice roughness deteriorates wind turbine aerodynamics. We have shown numerically that this also occurs when complex ice shapes are present on the leading edge, as long as the blade's wet region extends beyond the ice shape itself and roughness elements are high enough. Such features are typical of icing events on wind turbines but are not captured by current icing simulation tools. Future research should focus on correctly computing both the wet region of the blade and the roughness height.
Koen Boorsma, Gerard Schepers, Helge Aagard Madsen, Georg Pirrung, Niels Sørensen, Galih Bangga, Manfred Imiela, Christian Grinderslev, Alexander Meyer Forsting, Wen Zhong Shen, Alessandro Croce, Stefano Cacciola, Alois Peter Schaffarczyk, Brandon Lobo, Frederic Blondel, Philippe Gilbert, Ronan Boisard, Leo Höning, Luca Greco, Claudio Testa, Emmanuel Branlard, Jason Jonkman, and Ganesh Vijayakumar
Wind Energ. Sci., 8, 211–230, https://doi.org/10.5194/wes-8-211-2023, https://doi.org/10.5194/wes-8-211-2023, 2023
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Within the framework of the fourth phase of the International Energy Agency's (IEA) Wind Task 29, a large comparison exercise between measurements and aeroelastic simulations has been carried out. Results were obtained from more than 19 simulation tools of various fidelity, originating from 12 institutes and compared to state-of-the-art field measurements. The result is a unique insight into the current status and accuracy of rotor aerodynamic modeling.
Simone Mancini, Koen Boorsma, Gerard Schepers, and Feike Savenije
Wind Energ. Sci., 8, 193–210, https://doi.org/10.5194/wes-8-193-2023, https://doi.org/10.5194/wes-8-193-2023, 2023
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Modern wind turbines are subject to complex wind conditions that are far from the hypothesis of steady uniform inflow at the core of blade element momentum methods (the current industry standard for wind turbine design). Various corrections have been proposed to model this complexity. The present work focuses on modelling the unsteady evolution of wind turbine wakes (dynamic inflow), comparing the different corrections available and highlighting their effects on design load predictions.
Christian Grinderslev, Niels Nørmark Sørensen, Georg Raimund Pirrung, and Sergio González Horcas
Wind Energ. Sci., 7, 2201–2213, https://doi.org/10.5194/wes-7-2201-2022, https://doi.org/10.5194/wes-7-2201-2022, 2022
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As wind turbines increase in size, the risk of flow-induced instabilities increases. This study investigates the phenomenon of vortex-induced vibrations (VIVs) on a large 10 MW wind turbine blade using two high-fidelity methods. It is found that VIVs can occur with multiple equilibrium states for the same flow case, showing an dependence on the initial conditions. This means that a blade which is stable in a flow can become unstable if, e.g., a turbine operation provokes an initial vibration.
Felipe Vittori, José Azcona, Irene Eguinoa, Oscar Pires, Alberto Rodríguez, Álex Morató, Carlos Garrido, and Cian Desmond
Wind Energ. Sci., 7, 2149–2161, https://doi.org/10.5194/wes-7-2149-2022, https://doi.org/10.5194/wes-7-2149-2022, 2022
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This paper describes the results of a wave tank test campaign of a scaled SATH 10 MW INNWIND floating platform. The software-in-the-loop (SiL) hybrid method was used to include the wind turbine thrust and the in-plane rotor moments. Experimental results are compared with a numerical model developed in OpenFAST of the floating wind turbine. The results are discussed, identifying limitations of the numerical models and obtaining conclusions on how to improve them.
Thanasis Barlas, Georg Raimund Pirrung, Néstor Ramos-García, Sergio González Horcas, Ang Li, and Helge Aagaard Madsen
Wind Energ. Sci., 7, 1957–1973, https://doi.org/10.5194/wes-7-1957-2022, https://doi.org/10.5194/wes-7-1957-2022, 2022
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An aeroelastically optimized curved wind turbine blade tip is designed, manufactured, and tested on a novel outdoor rotating rig facility at the Risø campus of the Technical University of Denmark. Detailed aerodynamic measurements for various atmospheric conditions and results are compared to a series of in-house aeroelastic tools with a range of fidelities in aerodynamic modeling. The comparison highlights details in the ability of the codes to predict the performance of such a curved tip.
Jan-Philipp Küppers and Tamara Reinicke
Wind Energ. Sci., 7, 1889–1903, https://doi.org/10.5194/wes-7-1889-2022, https://doi.org/10.5194/wes-7-1889-2022, 2022
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Airfoils play a major role in the technical harnessing of energy from currents such as wind and water. When the angle of attack of a wing changes dynamically, the forces on the wing often change more than would have been assumed from static measurements alone. Since these dynamic forces have a strong influence, e.g., on the performance of airplanes and wind turbines, a neural-network-based model was created that can predict these loads and their stochastic fluctuations.
Frederik Berger, Lars Neuhaus, David Onnen, Michael Hölling, Gerard Schepers, and Martin Kühn
Wind Energ. Sci., 7, 1827–1846, https://doi.org/10.5194/wes-7-1827-2022, https://doi.org/10.5194/wes-7-1827-2022, 2022
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We proof the dynamic inflow effect due to gusts in wind tunnel experiments with MoWiTO 1.8 in the large wind tunnel of ForWind – University of Oldenburg, where we created coherent gusts with an active grid. The effect is isolated in loads and rotor flow by comparison of a quasi-steady and a dynamic case. The observed effect is not caught by common dynamic inflow engineering models. An improvement to the Øye dynamic inflow model is proposed, matching experiment and corresponding FVWM simulations.
Thomas Potentier, Emmanuel Guilmineau, Arthur Finez, Colin Le Bourdat, and Caroline Braud
Wind Energ. Sci., 7, 1771–1790, https://doi.org/10.5194/wes-7-1771-2022, https://doi.org/10.5194/wes-7-1771-2022, 2022
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A wind turbine blade equipped with root spoilers is analysed using time domain aeroelastic simulations to assess the impact of passive devices on the turbine AEP and lifetime. A novel way to account for aerofoil-generated unsteadiness in the fatigue calculation is proposed and detailed. The outcome shows that spoilers, on average, can increase the AEP of the turbine. However, the structural impacts on the turbine can be severe if not accounted for initially in the turbine design.
Alessandro Fontanella, Alan Facchinetti, Simone Di Carlo, and Marco Belloli
Wind Energ. Sci., 7, 1711–1729, https://doi.org/10.5194/wes-7-1711-2022, https://doi.org/10.5194/wes-7-1711-2022, 2022
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The aerodynamics of floating wind turbines is complicated by large motions permitted by the foundation. The interaction between turbine, wind, and wake is not yet fully understood. The wind tunnel experiments of this paper shed light on the aerodynamic force and wake response of the floating IEA 15 MW turbine subjected to platform motion as would occur during normal operation. This will help future research on turbine and wind farm control.
Emmanouil M. Nanos, Carlo L. Bottasso, Simone Tamaro, Dimitris I. Manolas, and Vasilis A. Riziotis
Wind Energ. Sci., 7, 1641–1660, https://doi.org/10.5194/wes-7-1641-2022, https://doi.org/10.5194/wes-7-1641-2022, 2022
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A novel way of wind farm control is presented where the wake is deflected vertically to reduce interactions with downstream turbines. This is achieved by moving ballast in a floating offshore platform in order to pitch the support structure and thereby tilt the wind turbine rotor disk. The study considers the effects of this new form of wake control on the aerodynamics of the steering and wake-affected turbines, on the structure, and on the ballast motion system.
Giorgia Guma, Philipp Bucher, Patrick Letzgus, Thorsten Lutz, and Roland Wüchner
Wind Energ. Sci., 7, 1421–1439, https://doi.org/10.5194/wes-7-1421-2022, https://doi.org/10.5194/wes-7-1421-2022, 2022
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Wind turbine aeroelasticity is becoming more and more important because turbine sizes are increasingly leading to more slender blades. On the other hand, complex terrains are of interest because they are far away from urban areas. These regions are characterized by low velocities and high turbulence and are mostly influenced by the presence of forest, and that is why it is necessary to develop high-fidelity tools to correctly simulate the wind turbine's response.
Cited articles
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Bech, J. I., Hasager, C. B., and Bak, C.: Extending the life of wind turbine blade leading edges by reducing the tip speed during extreme precipitation events, Wind Energ. Sci., 3, 729–748, https://doi.org/10.5194/wes-3-729-2018, 2018. a, b
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Short summary
The paper investigates the influence of the rain drop diameter on the formation of erosion damage and its implications for erosion-safe mode (ESM). By building an erosion damage model that incorporates several drop-size effects, we found that large droplets are significantly more erosive than small droplets. It is shown that the performance of the ESM is significantly increased when drop-size effects are correctly accounted for. A method to derive optimal ESM strategies is given as well.
The paper investigates the influence of the rain drop diameter on the formation of erosion...
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