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Wind Energy Science
The interactive open-access journal of the European Academy of Wind Energy
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Abstracted/indexed
Abstracted/indexed
Volume 2, issue 1
Wind Energ. Sci., 2, 241–256, 2017
https://doi.org/10.5194/wes-2-241-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/wes-2-241-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Special issue: The Science of Making Torque from Wind (TORQUE) 2016
Wind Energ. Sci., 2, 241–256, 2017
https://doi.org/10.5194/wes-2-241-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/wes-2-241-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article 16 May 2017
Research article | 16 May 2017
An investigation of unsteady 3-D effects on trailing edge flaps
Eva Jost et al.Related authors
No articles found.
Pascal Weihing, Tim Wegmann, Thorsten Lutz, Ewald Krämer, Timo Kühn, and Andree Altmikus
Wind Energ. Sci., 3, 503–531, https://doi.org/10.5194/wes-3-503-2018, https://doi.org/10.5194/wes-3-503-2018, 2018
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This research poses the question of whether rotor performance can be increased by an optimized design of the nacelle. For this purpose, the main geometrical parameters of the nacelle, such as the diameter, the relative position of the blade and the detailed shape in the junction of the blade, are investigated by means of computational fluid dynamics. By implementing a fairing-type shape in the junction, the detrimental flow separation in the inner part of the rotor could be eliminated.
Annette Claudia Klein, Sirko Bartholomay, David Marten, Thorsten Lutz, George Pechlivanoglou, Christian Navid Nayeri, Christian Oliver Paschereit, and Ewald Krämer
Wind Energ. Sci., 3, 439–460, https://doi.org/10.5194/wes-3-439-2018, https://doi.org/10.5194/wes-3-439-2018, 2018
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The paper describes the experimental and numerical investigation of a model wind turbine with a diameter of 3.0 m in a narrow wind tunnel. The objectives of the study are the provision of validation data, the comparison and evaluation of methods of different fidelity, and the assessment of the influence of wind tunnel walls. It turned out that the accordance between the experimental and numerical results is good, but the wind tunnel walls have to be taken into account for the present setup.
Related subject area
Aerodynamics and hydrodynamics
Performance study of the QuLAF pre-design model for a 10 MW floating wind turbine
Multi-element ducts for ducted wind turbines: a numerical study
Implementation of the Blade Element Momentum Model on a Polar Grid and its Aeroelastic Load Impact
A vortex-based tip/smearing correction for the actuator line
Brief communication: Wind speed independent actuator disk control for faster AEP calculations of wind farms using CFD
Power curve and wake analyses of the Vestas multi-rotor demonstrator
Qualitative yaw stability analysis of free-yawing downwind turbines
The aerodynamics of the curled wake: a simplified model in view of flow control
Wake behavior and control: comparison of LES simulations and wind tunnel measurements
Aerodynamic characterization of a soft kite by in situ flow measurement
Blind test comparison on the wake behind a yawed wind turbine
Advanced computational fluid dynamics (CFD)–multi-body simulation (MBS) coupling to assess low-frequency emissions from wind turbines
An efficient frequency-domain model for quick load analysis of floating offshore wind turbines
Probabilistic forecasting of wind power production losses in cold climates: a case study
Dynamic inflow effects in measurements and high-fidelity computations
Numerical analyses and optimizations on the flow in the nacelle region of a wind turbine
Simulation of transient gusts on the NREL 5 MW wind turbine using the URANS solver THETA
About the suitability of different numerical methods to reproduce model wind turbine measurements in a wind tunnel with a high blockage ratio
The second curvature correction for the straight segment approximation of periodic vortex wakes
Wind tunnel experiments on wind turbine wakes in yaw: effects of inflow turbulence and shear
How does turbulence change approaching a rotor?
Wind tunnel experiments on wind turbine wakes in yaw: redefining the wake width
Ducted wind turbine optimization and sensitivity to rotor position
Assessment of wind turbine component loads under yaw-offset conditions
Modeling of quasi-static thrust load of wind turbines based on 1 s SCADA data
Free-flow wind speed from a blade-mounted flow sensor
A model for quick load analysis for monopile-type offshore wind turbine substructures
Extraction of the wake induction and angle of attack on rotating wind turbine blades from PIV and CFD results
Modern methods for investigating the stability of a pitching floating platform wind turbine
Trailed vorticity modeling for aeroelastic wind turbine simulations in standstill
A validation and code-to-code verification of FAST for a megawatt-scale wind turbine with aeroelastically tailored blades
Aeroelastic stability of idling wind turbines
Design of advanced airfoil for stall-regulated wind turbines
Modal properties and stability of bend–twist coupled wind turbine blades
Vortex particle-mesh simulations of vertical axis wind turbine flows: from the airfoil performance to the very far wake
Joukowsky actuator disc momentum theory
Blind test comparison of the performance and wake flow between two in-line wind turbines exposed to different turbulent inflow conditions
Comparison of a coupled near- and far-wake model with a free-wake vortex code
Methodology for the engineering calculation of flaps on Wind Turbines using BEM codes
Actuator cylinder theory for multiple vertical axis wind turbines
Multi-fidelity fluid–structure interaction analysis of a membrane blade concept in non-rotating, uniform flow condition
Detailed analysis of the blade root flow of a horizontal axis wind turbine
Freddy J. Madsen, Antonio Pegalajar-Jurado, and Henrik Bredmose
Wind Energ. Sci., 4, 527–547, https://doi.org/10.5194/wes-4-527-2019, https://doi.org/10.5194/wes-4-527-2019, 2019
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This paper presents a comparison study of the simplified model QuLAF (Quick Load Analysis of Floating wind turbines) and FAST for the planar version of various design load cases, in order to investigate how accurate results can be obtained from this simplified model.
The overall analysis shows that QuLAF is generally very good at estimating the bending moment at the tower base and the floater motions, whereas the nacelle acceleration is generally underpredicted.
Vinit V. Dighe, Francesco Avallone, Ozer Igra, and Gerard van Bussel
Wind Energ. Sci., 4, 439–449, https://doi.org/10.5194/wes-4-439-2019, https://doi.org/10.5194/wes-4-439-2019, 2019
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Multi-element ducts are investigated to further improve the aerodynamic performance of ducted wind turbines. CFD simulations are performed for a multi-element duct geometry consisting of a duct and a flap; the goal is to evaluate the effects on the aerodynamic performance of the radial gap length and the deflection angle of the flap. Increasing the radial gap length results in an augmentation of the total thrust generated by the DWT, whereas a larger deflection angle has an opposite effect.
Helge Aagaard Madsen, Torben Juul Larsen, Georg Raimund Pirrung, Ang Li, and Frederik Zahle
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2019-53, https://doi.org/10.5194/wes-2019-53, 2019
Revised manuscript accepted for WES
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We show in the paper that the up scaling of turbines have led to new requirements in simulation of the unsteady aerodynamic forces by the engineering Blade Element Momentum (BEM) model, originally developed for simulation of the aerodynamics of propellers and helicopters. We present a new implementation of the BEM model on a polar grid which can be characterized as an engineering actuator disc model. The aeroelastic load impact of the new BEM implementation is analyzed and quantified.
Alexander R. Meyer Forsting, Georg Raimund Pirrung, and Néstor Ramos-García
Wind Energ. Sci., 4, 369–383, https://doi.org/10.5194/wes-4-369-2019, https://doi.org/10.5194/wes-4-369-2019, 2019
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The actuator line was intended as a lifting line technique for CFD applications. In this paper we prove – theoretically and practically – that smearing the forces of the actuator line in the flow domain leads to smeared velocity fields. By combining a near-wake representation of the trailed vorticity with a viscous vortex core model, the missing induction from the smeared velocity is recovered and a lifting line for CFD simulations established.
Maarten Paul van der Laan, Søren Juhl Andersen, and Pierre-Elouan Réthoré
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2019-27, https://doi.org/10.5194/wes-2019-27, 2019
Revised manuscript accepted for WES
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Wind farm layouts are designed by simple engineering wake models, which are fast to compute but also include a high uncertainty. Higher fidelity models, such as Reynolds-averaged Navier-Stokes, can be used to verify optimized wind farm layouts, although the computational cost are high due to the large number cases that are needed to calculate the annual energy production. This article presents a new wind turbine control method to speed up the high fidelity simulations by a factor 2–3.
Maarten Paul van der Laan, Søren Juhl Andersen, Néstor Ramos García, Nikolas Angelou, Georg Raimund Pirrung, Søren Ott, Mikael Sjöholm, Kim Hylling Sørensen, Julio Xavier Vianna Neto, Mark Kelly, Torben Krogh Mikkelsen, and Gunner Christian Larsen
Wind Energ. Sci., 4, 251–271, https://doi.org/10.5194/wes-4-251-2019, https://doi.org/10.5194/wes-4-251-2019, 2019
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Over the past few decades, single-rotor wind turbines have increased in size with the blades being extended toward lengths of 100 m. An alternative upscaling of turbines can be achieved by using multi-rotor wind turbines. In this article, measurements and numerical simulations of a utility-scale four-rotor wind turbine show that rotor interaction leads to increased energy production and faster wake recovery; these findings may allow for the design of wind farms with improved energy production.
Gesine Wanke, Morten Hartvig Hansen, and Torben Juul Larsen
Wind Energ. Sci., 4, 233–250, https://doi.org/10.5194/wes-4-233-2019, https://doi.org/10.5194/wes-4-233-2019, 2019
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In this paper the results of the stability analysis of a free-yawing downwind turbine are shown and the turbine's ability to align the rotor passively with the wind direction is investigated. The results show that a tilt angle causes the equilibrium yaw position of free-yawing downwind to be non-zero. It is shown that an increase in cone angle can stabilize the free-yaw mode significantly, while blade flapwise flexibility will increase the risk of an instability of the free-yaw mode.
Luis A. Martínez-Tossas, Jennifer Annoni, Paul A. Fleming, and Matthew J. Churchfield
Wind Energ. Sci., 4, 127–138, https://doi.org/10.5194/wes-4-127-2019, https://doi.org/10.5194/wes-4-127-2019, 2019
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A new control-oriented model is developed to compute the wake of a wind turbine under yaw. The model uses a simplified version of the Navier–Stokes equation with assumptions. Good agreement is found between the model-proposed and large eddy simulations of a wind turbine in yaw.
Jiangang Wang, Chengyu Wang, Filippo Campagnolo, and Carlo L. Bottasso
Wind Energ. Sci., 4, 71–88, https://doi.org/10.5194/wes-4-71-2019, https://doi.org/10.5194/wes-4-71-2019, 2019
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This paper describes an LES approach for the simulation of wind
turbines and their wakes. The simulation model is used to
develop a complete digital copy of experiments performed with
scaled wind turbines in a boundary layer wind tunnel, including the
passive generation of a sheared turbulent flow. Numerical results
are compared with experimental measurements, with a good overall
matching between the two.
Johannes Oehler and Roland Schmehl
Wind Energ. Sci., 4, 1–21, https://doi.org/10.5194/wes-4-1-2019, https://doi.org/10.5194/wes-4-1-2019, 2019
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We present an experimental method for aerodynamic characterization of flexible membrane kites by in situ measurement of the relative flow, while performing complex flight maneuvers. We find that the aerodynamics of this type of wing depend not only on the angle of attack, but also on the level of aerodynamic loading and the aeroelastic deformation. We recommend using the relative power setting of the kite as a secondary influencing parameter.
Franz Mühle, Jannik Schottler, Jan Bartl, Romain Futrzynski, Steve Evans, Luca Bernini, Paolo Schito, Martín Draper, Andrés Guggeri, Elektra Kleusberg, Dan S. Henningson, Michael Hölling, Joachim Peinke, Muyiwa S. Adaramola, and Lars Sætran
Wind Energ. Sci., 3, 883–903, https://doi.org/10.5194/wes-3-883-2018, https://doi.org/10.5194/wes-3-883-2018, 2018
Levin Klein, Jonas Gude, Florian Wenz, Thorsten Lutz, and Ewald Krämer
Wind Energ. Sci., 3, 713–728, https://doi.org/10.5194/wes-3-713-2018, https://doi.org/10.5194/wes-3-713-2018, 2018
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To get a better understanding of noise emissions from wind turbines at frequencies far below the audible range, simulations with increasing complexity were conducted. Consistent with the literature, it has been found that acoustic emission is dominated by the noise generated when the rotor blades pass the tower. These specific frequencies are less dominant in the structure-borne emission. Considering aerodynamic forces acting on the tower is important for the correct modeling of emissions.
Antonio Pegalajar-Jurado, Michael Borg, and Henrik Bredmose
Wind Energ. Sci., 3, 693–712, https://doi.org/10.5194/wes-3-693-2018, https://doi.org/10.5194/wes-3-693-2018, 2018
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This paper presents a simplified numerical model to quickly predict motion and loads of floating offshore wind turbines. Hydrodynamic, aerodynamic and mooring loads are extracted from higher-fidelity numerical tools. Without calibration, the model can predict with good accuracy the motions of the system in real wind and wave conditions. Loads at the tower base are estimated with errors between 0.2 % and 11.3 %. The model can simulate between 1300 and 2700 times faster than real time.
Jennie Molinder, Heiner Körnich, Esbjörn Olsson, Hans Bergström, and Anna Sjöblom
Wind Energ. Sci., 3, 667–680, https://doi.org/10.5194/wes-3-667-2018, https://doi.org/10.5194/wes-3-667-2018, 2018
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This study shows that using probabilistic forecasting can improve next-day production forecasts for wind energy in cold climates. Wind turbines can suffer from severe production losses due to icing on the turbine blades. Short-range forecasts including the icing-related production losses are therefore valuable when planning for next-day energy production. Probabilistic forecasting can also provide a likelihood for icing and icing-related production losses.
Georg Raimund Pirrung and Helge Aagaard Madsen
Wind Energ. Sci., 3, 545–551, https://doi.org/10.5194/wes-3-545-2018, https://doi.org/10.5194/wes-3-545-2018, 2018
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A wind turbine sees an overshoot in loading after a step change in pitch angle because the wake takes some time to reach a new equilibrium. The time constants of this dynamic inflow effect are expected to decrease significantly towards the blade tip. This radial dependency has not been found to the expected extent in previous analyses of force measurements from the NASA Ames Phase VI experiment. In the present article the findings from the experiment are explained based on a simple vortex model.
Pascal Weihing, Tim Wegmann, Thorsten Lutz, Ewald Krämer, Timo Kühn, and Andree Altmikus
Wind Energ. Sci., 3, 503–531, https://doi.org/10.5194/wes-3-503-2018, https://doi.org/10.5194/wes-3-503-2018, 2018
Short summary
Short summary
This research poses the question of whether rotor performance can be increased by an optimized design of the nacelle. For this purpose, the main geometrical parameters of the nacelle, such as the diameter, the relative position of the blade and the detailed shape in the junction of the blade, are investigated by means of computational fluid dynamics. By implementing a fairing-type shape in the junction, the detrimental flow separation in the inner part of the rotor could be eliminated.
Annika Länger-Möller
Wind Energ. Sci., 3, 461–474, https://doi.org/10.5194/wes-3-461-2018, https://doi.org/10.5194/wes-3-461-2018, 2018
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The capability of the DLR flow solver to simulate a wind turbine operating in an extreme gust event is presented by propagating the extreme gust through the flow field. The behaviour of the aerodynamic rotor loading and flow characteristics on the rotor blades were evaluated. The long-term perspective is to improve the understanding of the effects of instationary aerodynamics on the wind turbine. This will help to improve wind turbine design methods.
Annette Claudia Klein, Sirko Bartholomay, David Marten, Thorsten Lutz, George Pechlivanoglou, Christian Navid Nayeri, Christian Oliver Paschereit, and Ewald Krämer
Wind Energ. Sci., 3, 439–460, https://doi.org/10.5194/wes-3-439-2018, https://doi.org/10.5194/wes-3-439-2018, 2018
Short summary
Short summary
The paper describes the experimental and numerical investigation of a model wind turbine with a diameter of 3.0 m in a narrow wind tunnel. The objectives of the study are the provision of validation data, the comparison and evaluation of methods of different fidelity, and the assessment of the influence of wind tunnel walls. It turned out that the accordance between the experimental and numerical results is good, but the wind tunnel walls have to be taken into account for the present setup.
David H. Wood
Wind Energ. Sci., 3, 345–352, https://doi.org/10.5194/wes-3-345-2018, https://doi.org/10.5194/wes-3-345-2018, 2018
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The vortices in the wakes of wind turbines are often approximated by short, straight vortex segments, which cannot reproduce the curvature singularity in the induced velocity. They can also have a second error due to the periodicity: the vortices return to close proximity of the point at which the velocity is calculated. The second error is assessed by representing the far wake of a turbine as a row of vortex rings. The error is quantified and a simple correction is developed.
Jan Bartl, Franz Mühle, Jannik Schottler, Lars Sætran, Joachim Peinke, Muyiwa Adaramola, and Michael Hölling
Wind Energ. Sci., 3, 329–343, https://doi.org/10.5194/wes-3-329-2018, https://doi.org/10.5194/wes-3-329-2018, 2018
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Wake steering by yawing a wind turbine offers great potential to increase the wind farm power production. A model scale experiment in a controlled wind tunnel environment has been performed to map the wake flow's complex velocity distribution for different inflow conditions. A non-uniform sheared inflow was observed to affect the wake flow only insignificantly. The level of turbulent velocity fluctuations in the inflow, however, influenced the wake's velocity distribution to a higher degree.
Jakob Mann, Alfredo Peña, Niels Troldborg, and Søren J. Andersen
Wind Energ. Sci., 3, 293–300, https://doi.org/10.5194/wes-3-293-2018, https://doi.org/10.5194/wes-3-293-2018, 2018
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Turbulence is usually assumed to be unmodified by the stagnation occurring in front of a wind turbine rotor. All manufacturers assume this in their dynamic load calculations. If this assumption is not true it might bias the load calculations and the turbines might not be designed optimally. We investigate the assumption with a Doppler lidar measuring forward from the top of the nacelle and find small but systematic changes in the approaching turbulence that depend on the power curve.
Jannik Schottler, Jan Bartl, Franz Mühle, Lars Sætran, Joachim Peinke, and Michael Hölling
Wind Energ. Sci., 3, 257–273, https://doi.org/10.5194/wes-3-257-2018, https://doi.org/10.5194/wes-3-257-2018, 2018
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In this work, the wake flows behind two different model wind turbines were investigated in wind tunnel experiments user laser Doppler anemometry. It was found that the width of the wake flow is significantly dependent on the quantities examined, becoming much wider when taking higher-order statistics into account. This effect is stable against yaw misalignment and thus affects not only wind farm layout optimizations but also the applicability of active wake steering methods.
Nojan Bagheri-Sadeghi, Brian T. Helenbrook, and Kenneth D. Visser
Wind Energ. Sci., 3, 221–229, https://doi.org/10.5194/wes-3-221-2018, https://doi.org/10.5194/wes-3-221-2018, 2018
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Simulations were used to design ducted wind turbines with the objective of either maximizing power per rotor area (PPRA) or maximizing power per duct exit area (PPDA). When PPRA is maximized, any rotor position within the first half of the duct produces approximately the same PPRA. When PPDA is maximized, the optimal position of the rotor is at the rear of duct. In this case, the PPDA exceeds the theoretical power per unit area that can be produced by an open rotor.
Rick Damiani, Scott Dana, Jennifer Annoni, Paul Fleming, Jason Roadman, Jeroen van Dam, and Katherine Dykes
Wind Energ. Sci., 3, 173–189, https://doi.org/10.5194/wes-3-173-2018, https://doi.org/10.5194/wes-3-173-2018, 2018
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The paper discusses load effects on wind turbines operating under misaligned-flow operations, which is part of a strategy to optimize wind-power-plant power production, where upwind turbines can be rotated off the wind axis to redirect their wakes. Analytical simplification, aeroelastic simulations, and field data from an instrumented turbine are compared and interpreted to provide an informed picture on the loads for various components.
Nymfa Noppe, Wout Weijtjens, and Christof Devriendt
Wind Energ. Sci., 3, 139–147, https://doi.org/10.5194/wes-3-139-2018, https://doi.org/10.5194/wes-3-139-2018, 2018
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A reliable load history is crucial for a fatigue assessment of wind turbines. However, installing strain sensors to measure the load history on every wind turbine is not economically feasible. In this paper, a technique is proposed to reconstruct the thrust load history of a wind turbine based on high-frequency SCADA data and a trained neural network. Both simulated and real-world results show the potential of high-frequency SCADA for thrust load reconstruction.
Mads Mølgaard Pedersen, Torben Juul Larsen, Helge Aagaard Madsen, and Søren Juhl Andersen
Wind Energ. Sci., 3, 121–138, https://doi.org/10.5194/wes-3-121-2018, https://doi.org/10.5194/wes-3-121-2018, 2018
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The wind speed measured by a flow sensor mounted on the blade of a wind turbine is disturbed by the turbine. This paper presents a method to obtain the free turbulence inflow by compensating for this disturbance.
The method is tested using numerical simulations and can be used to extract inflow information for accurate aeroelastic load simulations.
Signe Schløer, Laura Garcia Castillo, Morten Fejerskov, Emanuel Stroescu, and Henrik Bredmose
Wind Energ. Sci., 3, 57–73, https://doi.org/10.5194/wes-3-57-2018, https://doi.org/10.5194/wes-3-57-2018, 2018
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A model for quick load analysis is presented. This is a fast model for the calculation of dynamic loads of an offshore wind turbine tower and foundation. The model is compared to the state-of-the-art aeroelastic code. In general, there is good similarity between the two models. This indicates that in the early stage of the design phase a simple dynamic model can be used to make a preliminary design of the foundation and wind turbine tower.
Iván Herráez, Elia Daniele, and J. Gerard Schepers
Wind Energ. Sci., 3, 1–9, https://doi.org/10.5194/wes-3-1-2018, https://doi.org/10.5194/wes-3-1-2018, 2018
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Several methods have been proposed in the past for extracting the blade performance of wind turbines from simulations. In this work, we present a new method that allows obtaining those data easily not only from simulation results but also from flow measurements. We apply the method to both experiments and simulations of a well-known wind turbine model. The results provide insight into the wind turbine aerodynamics and open up new possibilities for the validation of simulation models.
Matthew Lennie, David Marten, George Pechlivanoglou, Christian Navid Nayeri, and Christian Oliver Paschereit
Wind Energ. Sci., 2, 671–683, https://doi.org/10.5194/wes-2-671-2017, https://doi.org/10.5194/wes-2-671-2017, 2017
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Floating platform wind turbines present a challenge for engineers to simulate. This paper explores some better methods for simulating the aerodynamics of wind turbines as they move about on a floating platform. We also derived a new way of investigating whether the aerodynamics of the wind turbine rotor help it stay stable.
Georg R. Pirrung, Helge A. Madsen, and Scott Schreck
Wind Energ. Sci., 2, 521–532, https://doi.org/10.5194/wes-2-521-2017, https://doi.org/10.5194/wes-2-521-2017, 2017
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Current fast aeroelastic wind turbine codes suitable for certification lack an induction model for standstill conditions. A near-wake model for wind turbines in operation is extended to cover these conditions. The model is validated in aerodynamic simulations of the NREL/NASA Ames Phase VI rotor. Good agreement with the experiments has been obtained in attached flow and beginning separation. Aeroelastic simulations of the DTU 10 MW turbine in standstill indicate a minor impact of the model.
Srinivas Guntur, Jason Jonkman, Ryan Sievers, Michael A. Sprague, Scott Schreck, and Qi Wang
Wind Energ. Sci., 2, 443–468, https://doi.org/10.5194/wes-2-443-2017, https://doi.org/10.5194/wes-2-443-2017, 2017
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This paper presents a validation and code-to-code verification of the U.S. Dept of Energy/NREL wind turbine aeroelastic code, FAST v8, on a 2.3 MW wind turbine. Model validation is critical to any model-based research and development activity, and validation efforts on large turbines, as the current one, are extremely rare, mainly due to the scale. This paper, which was a collaboration between NREL and Siemens Wind Power, successfully demonstrates and validates the capabilities of FAST.
Kai Wang, Vasilis A. Riziotis, and Spyros G. Voutsinas
Wind Energ. Sci., 2, 415–437, https://doi.org/10.5194/wes-2-415-2017, https://doi.org/10.5194/wes-2-415-2017, 2017
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In the paper, rotor stability in slow idling operation is assessed on the basis of nonlinear time domain and linear eigenvalue analyses. A consistent and computationally cost effective modeling environment has been presented for the analysis of parked or idling rotors. The analysis shows that the lowest damped modes of a 10 MW idling rotor are out-of-plane modes (symmetric and asymmetric).
Francesco Grasso, Domenico Coiro, Nadia Bizzarrini, and Giuseppe Calise
Wind Energ. Sci., 2, 403–413, https://doi.org/10.5194/wes-2-403-2017, https://doi.org/10.5194/wes-2-403-2017, 2017
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The majority of the wind turbine market is focused on large pitch-regulated machines, but small stall-regulated are still attractive because of their simplicity and robustness. This work focuses on aerodynamic section design for these machines and its impact on overall performance. The big challenge faced was that, beside the need to maximise the energy produced, the control of the machine depends on the section design. The results, however, showed a large performance gain and machine control.
Alexander R. Stäblein, Morten H. Hansen, and David R. Verelst
Wind Energ. Sci., 2, 343–360, https://doi.org/10.5194/wes-2-343-2017, https://doi.org/10.5194/wes-2-343-2017, 2017
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Coupling between bending and twist has a significant influence on the aeroelastic response of wind turbine blades. The coupling can arise from the blade geometry or from the anisotropic properties of the blade material. Bend–twist coupling can be utilised to reduce the fatigue loads of wind turbine blades. In this study the effects of material-based coupling on the aeroelastic modal properties and stability limits of the DTU 10 MW Reference Wind Turbine are investigated.
Philippe Chatelain, Matthieu Duponcheel, Denis-Gabriel Caprace, Yves Marichal, and Grégoire Winckelmans
Wind Energ. Sci., 2, 317–328, https://doi.org/10.5194/wes-2-317-2017, https://doi.org/10.5194/wes-2-317-2017, 2017
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Vertical axis wind turbines (VAWTs) operate through inherently unsteady aerodynamics, unlike their horizontal axis counterparts (HAWTs). This greatly affects the structure of the wake, i.e., the region of velocity deficit and increased turbulence downstream of the machine. In this work, we use an advanced vortex method to identify the flow structures and instabilities at work in the decay of a VAWT wake, a crucial step if one wishes to optimize this decay or perform the design of VAWT farms.
Gijs A. M. van Kuik
Wind Energ. Sci., 2, 307–316, https://doi.org/10.5194/wes-2-307-2017, https://doi.org/10.5194/wes-2-307-2017, 2017
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Actuator disc theory is the basis of most rotor design methods. However, the off-design condition of a very low rotational speed Ω is still a topic for scientific discussions. A small modification in the momentum theory for Joukowsky discs with uniform circulation results in the efficiency going to 0 instead of ∞ when Ω goes to 0. For high values of Ω, the classical momentum theory is reproduced. The new theory is confirmed by a very good match with numerically obtained results.
Jan Bartl and Lars Sætran
Wind Energ. Sci., 2, 55–76, https://doi.org/10.5194/wes-2-55-2017, https://doi.org/10.5194/wes-2-55-2017, 2017
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As wind turbines extract energy from the wind, a wind field of reduced wind speed and increased turbulence is left behind for the downstream turbines. For the exact calculation of the annual energy production and lifetime of wind turbines, it is therefore of great importance to be able to accurately calculate this turbulent wake flow for different wind conditions. This paper compares different computational modeling approaches with flow measurements on model turbines in a wind tunnel.
Georg Pirrung, Vasilis Riziotis, Helge Madsen, Morten Hansen, and Taeseong Kim
Wind Energ. Sci., 2, 15–33, https://doi.org/10.5194/wes-2-15-2017, https://doi.org/10.5194/wes-2-15-2017, 2017
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The certification process of a wind turbine requires simulations of a coupled structural and aerodynamic wind turbine model in many different external conditions. Due to the large number of load cases, the complexity of the aerodynamics models has to be limited. In this paper, a simplified vortex method based aerodynamics model is described. It is shown that this model, which is fast enough for use in a certification context, can produce results similar to those of a more complex vortex model.
Maria Aparicio-Sanchez, Alvaro Gonzalez-Salcedp, Sugoi Gomez-Iradi, and Xabier Munduate
Wind Energ. Sci. Discuss., https://doi.org/10.5194/wes-2016-50, https://doi.org/10.5194/wes-2016-50, 2016
Publication in WES not foreseen
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The use of the flaps is one of the options to reduce the equivalent loads or to increase the power in large wind turbines. This paper presents a methodology to simulate the performance of the blades with these aerodynamic devices. This method presents important advantages with respect to CFD in terms of computational effort and leads to similar results.
Andrew Ning
Wind Energ. Sci., 1, 327–340, https://doi.org/10.5194/wes-1-327-2016, https://doi.org/10.5194/wes-1-327-2016, 2016
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Wind turbines rarely operate in isolation but rather in close proximity within wind farms. Currently analysis methods are designed for analyzing turbines in isolation, or within a waked region. Actuator cylinder theory is extended to handle multiple vertical axis wind turbines in close proximity. We find good agreement in power predictions as compared to available higher-fidelity simulation data. The corresponding code may be useful for conceptual design and has been fully open-sourced.
Mehran Saeedi, Kai-Uwe Bletzinger, and Roland Wüchner
Wind Energ. Sci., 1, 255–269, https://doi.org/10.5194/wes-1-255-2016, https://doi.org/10.5194/wes-1-255-2016, 2016
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Fluid–structure interaction analysis of a membrane blade concept has been performed for a non-rotating blade under steady inflow conditions. The membrane blade consists of a rigid mast at the leading edge, ribs along the blade, tensioned edge cables at the trailing edge, and membranes forming the upper and lower surface of the blade. The studied membrane blade shows a higher lift curve slope and higher lift-to-drag ratio compared with its rigid-blade counterpart.
Iván Herráez, Buşra Akay, Gerard J. W. van Bussel, Joachim Peinke, and Bernhard Stoevesandt
Wind Energ. Sci., 1, 89–100, https://doi.org/10.5194/wes-1-89-2016, https://doi.org/10.5194/wes-1-89-2016, 2016
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The flow in the blade root region of horizontal axis wind turbines is highly three-dimensional. Furthermore, it is influenced by the presence of strong trailing vortices. In this work we study the complex root flow by means of experiments and numerical simulations. The simulations are shown to be reliable at predicting the main flow features of the rotor blades. Additionally, new insight into the physical mechanisms governing the blade root aerodynamics is given.
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Trailing edge flaps applied to the outer part of a wind turbine rotor blade are a very promising concept to reduce fatigue loads as they are able to increase or decrease the airfoil lift for a given angle of attack. They have been widely researched on 2-D airfoils, but only little is known about their aerodynamic characteristics on 3-D wind turbine rotor blades. The present article addresses this issue.
Trailing edge flaps applied to the outer part of a wind turbine rotor blade are a very promising...
Wind Energy Science
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