Hansen, Kurt Schaldemose

Ivanell, S.

Uzunoglu, B.

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 20, 2017Benchmarking of non-linear wake interaction of eddy viscosity modelUzunoglu, B.; Hansen, Kurt Schaldemose; Ivanell, S.Publication date:2012Link back to DTU OrbitCitation (APA):Uzunoglu, B., Hansen, K. S., & Ivanell, S. (2012). Benchmarking of non-linear wake interaction of eddy viscositymodel. Abstract from The science of Making Torque from Wind 2012, Oldenburg, Germany.OldenburgBENCHMARKING OF NON-LINEAR WAKE INTERACTION OF EDDYVISCOSITY MODELB.Uzunoglu, K.Hansen and S.IvanellGotland University,Cramergatan 3 621 57 Visby, Swedene-mail: bahri.uzunoglu@hgo.see-mail: stefan.ivanell@hgo.se†Department of Wind EnergyTechnical University of DenmarkNils Koppels Alle Building 403, room 2182800 Kgs. Lyngby Denmarke-mail: kuhan@dtu.dkKey words: Eddy Viscosity Model, Nonlinear Wake, Lidar, ReducedAbstract. Modelling of wake losses is an important part of the production estimation for windfarms. The eddy viscosity model is widely adapted by industry for wind farm wake calculationsand energy output predictions 1. Their practical implementations for linear wind resource gridgeneration tools and their ability to provide better accuracy in non-linear terms and turbulenceterms 1,2,3,4 created easy market penetration. As a result, the eddy viscosity wake models andtheir variants have found wide spread application in commercial wind farm design softwares.Compared to algebraic wake models, eddy viscosity model has intermediate complexity inphysics. The referred model can be derived by simplification of Reynolds Averaged Navier-Stokesequations. This derivation reduces the complexity of the model compared to full CFD models 5.The eddy viscosity model is derived by employing velocity deficit field using the thin shear layerapproximation in axi-symmetric coordinates.The eddy viscosity model’s wake comparison has been limited to either CFD results comparisonor to wind tunnel tests to this day 2,14. By introduction of more advanced spatial measurementstechniques such as Lidar, it is now possible to have more detailed field comparison and validationto actual wind turbine measurements recently 1.In this work, eddy-viscosity will be benchmarked to non-linear models such as actuator discmodel in two turbine settings and to recently available Lidar data 1. This gives us further insightinto the application envelope of the eddy viscosity model. The impact of different parameterson velocity deficit and turbulence approaches will be investigated. Power deficit as a functionof ambient turbulence intensity will be validated. The impact of central speed deficit created byshadowing will be implemented to initial profile1.1B.Uzunoglu, K.Hansen and S.IvanellREFERENCES[1] The impact of turbulence intensity and atmospheric stability on power deficits dueto wind turbine wakes at Horns Rev wind farm Wind Energy, Special Issue, 2011.[2] Windfarmer, The wind farm design software, Theory Manual (11/2006) Garrad Has-san and Partners LTD..[3] Openwind, Theoretical basis and validation Version 1.3 (04/2010) AWSTRUE-POWER LLC.[4] WindPRO / PARK, Introduction to Wind Turbine Wake Modelling and Wake Gen-erated Turbulence (04/2005) EMD International A/S.[5] B.Lange, H.P.Waldi, A.G.Guerrero, D. Heinemann and R. Barthelmie Modelling ofOffshore Wind Turbine Wakes with the Wind Farm Program FLaP Wind Energy,37, 87–104 (2003).[6] J.F.Ainslie Calculating the velocity field in the wake of wind turbines. Journal ofWind Engineering and Industrial Aerodynamics, 27, 213–224 (1988).[7] S.Ivanell Numerical computation of wind turbine wakes. PhD thesis, ISSN 0348-467X, KTH., (2005).[8] F.Zou Estimation of wind energy production for Offshore wind farm. MSc thesis,KTH., (2011).[9] WindSim. History. http://windsim.com/about-windsim/history.aspx. Accessed:2010-07-15.[10] Windfarmer 4.1, Validation report (11/2006) Garrad Hassan and Partners LTD..[11] B.Uzunoglu Reduced modelling and controller design for boundary element dis-cretized flow around cylinders. PhD thesis, University of Southampton., (2001).[12] C.Sanz A note on k  modelling of vegetation canopy air-flows. Boundary-LayerMeteorology, 108, 191-197 (2003).[13] A.Sogachev A note on two-equation closure modelling of canopy. Boundary-LayerMeteorology, 130, 423-435 (2009).[14] B.Uzunoglu, F.Zou and S.Ivanell Benchmarking of eddy viscosity model with non-linear wake models CFD Optimization 2011, 071, 23-25 May 2011, Antalya Turkey.2

Benchmarking of non-linear wake interaction of eddy viscosity model

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Benchmarking of non-linear wake interaction of eddy viscosity model

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