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Wind power wake modelling: Development and application of an actuator disc method for industrial utilization.
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

As a wind turbine extracts energy from the wind it creates a region downstream where the wind velocity is decreased and the urbulence intensity is increased, this region is commonly called the wake region. Today’s wind farms include a large number of wind turbines position in tight layouts. These tight layouts result in increased power losses due to wakes, rendering accurate wind turbine wake modelling crucial in developing cost effective projects.

The primary aim of this study is to create a method capable of conducting full-scale wind farm wake computations accurately in a time efficient manner by taking into account the computational resources and data availability of a typical industrial user. As a first step of this study, an actuator disc (ACD) method (old ACD) used within WindSim, is evaluated against power production data from the Lillgrund offshore wind. This study is followed by the development of a new ACD method. The new ACD method differs from the previous ACD method in terms of how the thrust distribution and the power production is calculated. A series of validation studies are performed on this newly introduced ACD method. These consist of validating the method against two cases with known analytical solutions, the research code EllipSys3D which uses Large Eddy Simulation (LES) based computations with an ACD approach and three differentwind tunnel set–ups. Lastly, a comparative analysis of the two ACD methods (old and new) and two analytical wake models is done using wind turbine power production data from Lillgrund.

Results from the validation studies show that this new ACD method is able to predict the overall behaviour of the flow with low computational effort while also taking into account the availability of data for a typical industrial user. One may say that the new ACD method in RANS, which has much lower computational requirements than the ACD method in LES at the cost of lower accuracy, represents a good compromise. Lastly, the results from the new ACD method show a clear improvement in the estimated power production for the Lillgrund wind farm in comparison to the old ACD method.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. , p. 50
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1680
Keywords [en]
Wind power, Offshore wind farm, Wakes, Actuator Disc Method (ACD), Computational Fluid Dynamics (CFD), Reynolds Average Navier–Stokes (RANS), WindSim, PHOENICS
National Category
Earth and Related Environmental Sciences
Identifiers
URN: urn:nbn:se:uu:diva-350028ISBN: 978-91-513-0357-4 (print)OAI: oai:DiVA.org:uu-350028DiVA, id: diva2:1203292
Public defence
2018-09-12, E22, Campus Gotland, Cramérgatan 3, Visby, 10:15 (English)
Opponent
Supervisors
Available from: 2018-06-13 Created: 2018-05-03 Last updated: 2018-09-27
List of papers
1. Numerical CFD comparison of Lillgrund employing RANS EERA
Open this publication in new window or tab >>Numerical CFD comparison of Lillgrund employing RANS EERA
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2014 (English)Conference paper, Oral presentation only (Refereed)
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-238295 (URN)
Conference
DeepWind 2014, 11th Deep Sea Offshore Wind R&D Conference
Funder
StandUp for Wind
Available from: 2014-12-11 Created: 2014-12-11 Last updated: 2018-05-03
2. Description and validation of the actuator disc approach in PHOENICS.
Open this publication in new window or tab >>Description and validation of the actuator disc approach in PHOENICS.
2016 (English)Report (Other (popular science, discussion, etc.))
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-350027 (URN)
Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2018-05-03
3. Validation of the actuator disc approach using small-scale model wind turbines
Open this publication in new window or tab >>Validation of the actuator disc approach using small-scale model wind turbines
2017 (English)In: Wind Energy Science, ISSN 2213-3968, E-ISSN 2366-7443, Vol. 2, p. 587-601Article in journal (Refereed) Published
Abstract [en]

The aim of the present study is the validation of the implementation of an actuator disc (ACD) model in the computational fluid dynamics (CFD) code PHOENICS. The flow behaviour for three wind turbine cases is investigated numerically and compared to wind tunnel measurements: (A) the flow around a single model wind turbine, (B) the wake interaction between two in-line model wind turbines for a uniform inflow of low turbulence intensity and (C) the wake interaction between two in-line model wind turbines at different separation distances in a uniform or sheared inflow of high turbulence intensity. This is carried out using Reynolds-averaged Navier–Stokes (RANS) simulations and an ACD technique in the CFD code PHOENICS. The computations are conducted for the design condition of the rotors using four different turbulence closure models and five different thrust distributions. The computed axial velocity field as well as the turbulence kinetic energy are compared with hot-wire anemometry (HWA) measurements. For the cases with two in-line wind turbines, the thrust coefficient is also computed and compared with measurements. The results show that for different inflow conditions and wind turbine spacings the proposed method is able to predict the overall behaviour of the flow with low computational effort. When using the k-ε and Kato–Launder k-ε turbulence models the results are generally in closer agreement with the measurements.

National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:uu:diva-338124 (URN)10.5194/wes-2-587-2017 (DOI)000416160500001 ()
Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2018-05-03Bibliographically approved
4. The actuator disc concept in PHOENICS
Open this publication in new window or tab >>The actuator disc concept in PHOENICS
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2016 (English)In: Energy Procedia / [ed] Tande, JOG; Kvamsdal, T; Muskulus, M, 2016, Vol. 94, p. 269-277Conference paper, Published paper (Refereed)
Abstract [en]

This study presents two models to simulate a wind turbine. This is done by employing the 1D momentum actuator disc theory in PHOENICS, a general purpose computational fluid dynamics software. To test the general applicability of these models, single wind turbine simulations are conducted using eight different wind turbine models from two manufacturers. The simulations are performed by imposing sheared inflow with hub height wind speeds ranging from 3 m/s up to 25 m/s. A range of computational parameters are investigated, including the resolution of the domain, the thickness of the actuator disc and the iterative convergence criteria. To investigate the wake development produced by these methods, a comparison study is performed with the more complex large-eddy simulation software EllipSys3D using an actuator disc approach for validation purposes. The resulting wind turbine thrust and power outputs from PHOENICS are compared with the experimental power curves and thrust values provided by the manufacturers for each wind turbine. The results show that actuator disc methods are able to provide a reasonable estimation of the conventional wind turbine power and thrust output with low computational effort. Moreover, the results from the preliminary comparison of the wake produced from these two rotor models compare well with the wake produced by the actuator disc in EllipSys3D.

Series
Energy Procedia, ISSN 1876-6102 ; 94
Keywords
Wind energy, Computational Fluid Dynamics (CFD), Reynolds averaged Navier-Stokes (RANS), Actuator Disc (ACD), Large-eddy simulation (LES)
National Category
Earth and Related Environmental Sciences Environmental Engineering
Identifiers
urn:nbn:se:uu:diva-306640 (URN)10.1016/j.egypro.2016.09.182 (DOI)000387586600028 ()
Conference
13th Deep Sea Offshore Wind R&D Conference, EERA DeepWind’ JAN 20-22, 2016, Trondheim, Norway
Funder
StandUp for Wind
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2018-05-03Bibliographically approved
5. Wind farm power production assessment: a comparative analysis of two actuator disc methods and two analytical wake models
Open this publication in new window or tab >>Wind farm power production assessment: a comparative analysis of two actuator disc methods and two analytical wake models
2018 (English)In: Wind Energy Science, ISSN 2213-3968, E-ISSN 2366-7443, Vol. 2018, p. 1-13Article in journal (Refereed) Epub ahead of print
Abstract [en]

The aim of the present study is to perform a comparative analysis of two actuator disc methods (ACD) and two analytical wake models for wind farm power production assessment. To do so wind turbine power production data from the Lillgrund offshore wind farm in Sweden is used. The measured power production for individual wind turbines is compared with results from simulations, done in the WindSim software, using two ACD methods (old and new) and two analytical wake models widely used within the wind industry (Jensen and Larsen wake models). It was found that the new ACD method and the Larsen model outperform the other method and model in most cases. Furthermore, results from the new ACD method show a clear improvement in the estimated power production in comparison to the old ACD method. The Jensen method seems to overestimate the power deficit for all cases. The new ACD method, despite it's simplicity, is capable of capturing the power production within the given error margin although it tends to underestimate the power deficit.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-350026 (URN)10.5194/wes-2018-8 (DOI)
Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2018-05-07Bibliographically approved
6. Validation of the actuator disc approach inPHOENICS using small scale model wind turbines
Open this publication in new window or tab >>Validation of the actuator disc approach inPHOENICS using small scale model wind turbines
2016 (English)In: Journal of Physics: Conference Series, 2016, Vol. 753, p. 032-028Conference paper, Published paper (Refereed)
Abstract [en]

In this study two wind turbine setups are investigated numerically: (a) the flow around a single model wind turbine and (b) the wake interaction between two in-line model wind turbines. This is done by using Reynolds averaged Navier-Stokes (RANS) and an actuator disc (ACD) technique in the computational fluid dynamics code PHOENICS. The computations are conducted for the design condition of the rotors using four different turbulence closure models. The computed axial velocity field as well as the turbulent kinetic energy are compared with PIV measurements. For the two model wind turbine setup, the thrust and power coefficient are also computed and compared with measurements. The results show that this RANS ACD method is able to predict the overall behaviour of the flow with low computational effort and that the turbulence closure model has a direct effect on the predicted wake development.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-306642 (URN)10.1088/1742-6596/753/3/032028 (DOI)
Conference
Science of Making Torque from Wind
Funder
StandUp for Wind
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2018-05-03

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Simisiroglou, Nikolaos

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