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Calibration and validation of the dynamic wake meandering model for implementation in an aeroelastic code / H. Aa. Madsen in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041014/1-14] Titre : Calibration and validation of the dynamic wake meandering model for implementation in an aeroelastic code Type de document : texte imprimé Auteurs : H. Aa. Madsen, Auteur ; G. C. Larsen, Auteur ; T. J. Larsen, Auteur Année de publication : 2011 Article en page(s) : pp. [041014/1-14] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Actuators  Calibration  Discs  (structures)  Elasticity  Turbulence  Vortices  Wakes  Wind  power  plants  Wind  turbines Index. décimale : 621.47 Résumé : As the major part of new wind turbines are installed in clusters or wind farms, there is a strong need for reliable and accurate tools for predicting the increased loadings due to wake operation and the associated reduced power production. The dynamic wake meandering (DWM) model has been developed on this background, and the basic physical mechanisms in the wake—i.e., the velocity deficit, the meandering of the deficit, and the added turbulence—are modeled as simply as possible in order to make fast computations. In the present paper, the DWM model is presented in a version suitable for full integration in an aeroelastic model. Calibration and validation of the different parts of the model is carried out by comparisons with actuator disk and actuator line (ACL) computations as well as with inflow measurements on a full-scale 2 MW turbine. It is shown that the load generating part of the increased turbulence in the wake is due almost exclusively to meandering of the velocity deficit, which causes “apparent” turbulence when measuring the flow in a fixed point in the wake. Added turbulence, originating mainly from breakdown of tip vortices and from the shear of the velocity deficit, has only a minor contribution to the total turbulence and with a small length scale in the range of 10–25% of the ambient turbulence length scale. Comparisons of the calibrated DWM model with ACL results for different downstream positions and ambient turbulence levels show good correlation for both wake deficits and turbulence levels. Finally, added turbulence characteristics are compared with correlation results from literature. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Calibration and validation of the dynamic wake meandering model for implementation in an aeroelastic code [texte imprimé] / H. Aa. Madsen, Auteur ; G. C. Larsen, Auteur ; T. J. Larsen, Auteur . - 2011 . - pp. [041014/1-14]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041014/1-14] Mots-clés : Actuators  Calibration  Discs  (structures)  Elasticity  Turbulence  Vortices  Wakes  Wind  power  plants  Wind  turbines Index. décimale : 621.47 Résumé : As the major part of new wind turbines are installed in clusters or wind farms, there is a strong need for reliable and accurate tools for predicting the increased loadings due to wake operation and the associated reduced power production. The dynamic wake meandering (DWM) model has been developed on this background, and the basic physical mechanisms in the wake—i.e., the velocity deficit, the meandering of the deficit, and the added turbulence—are modeled as simply as possible in order to make fast computations. In the present paper, the DWM model is presented in a version suitable for full integration in an aeroelastic model. Calibration and validation of the different parts of the model is carried out by comparisons with actuator disk and actuator line (ACL) computations as well as with inflow measurements on a full-scale 2 MW turbine. It is shown that the load generating part of the increased turbulence in the wake is due almost exclusively to meandering of the velocity deficit, which causes “apparent” turbulence when measuring the flow in a fixed point in the wake. Added turbulence, originating mainly from breakdown of tip vortices and from the shear of the velocity deficit, has only a minor contribution to the total turbulence and with a small length scale in the range of 10–25% of the ambient turbulence length scale. Comparisons of the calibrated DWM model with ACL results for different downstream positions and ambient turbulence levels show good correlation for both wake deficits and turbulence levels. Finally, added turbulence characteristics are compared with correlation results from literature. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Trailing edge noise model validation and application to airfoil optimization / F. Bertagnolio in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 3 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031010/1-9] Titre : Trailing edge noise model validation and application to airfoil optimization Type de document : texte imprimé Auteurs : F. Bertagnolio, Auteur ; H. Aa. Madsen, Auteur ; C. Bak, Auteur Année de publication : 2011 Article en page(s) : pp. [031010/1-9] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Aerodynamics  Noise  abatement  Noise  measurement  Optimisation  Wind  turbines Index. décimale : 621.47 Résumé : The aim of this article is twofold. First, an existing trailing edge noise model is validated by comparing with airfoil surface pressure fluctuations and far field sound pressure levels measured in three different experiments. The agreement is satisfactory in one case but poor in two other cases. Nevertheless, the model reproduces the main tendencies observed in the measurements with respect to varying flow conditions. Second, the model is implemented into an airfoil design code that is originally used for aerodynamic optimization. An existing wind turbine airfoil is optimized in order to reduce its noise emission, trying at the same time to preserve some of its aerodynamic and geometric characteristics. The new designs are characterized by less cambered airfoils and flatter suction sides. The resulting noise reductions seem to be mainly achieved by a reduction in the turbulent kinetic energy across the boundary layer near the trailing edge and to a lesser extent by a smaller boundary layer displacement thickness. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Trailing edge noise model validation and application to airfoil optimization [texte imprimé] / F. Bertagnolio, Auteur ; H. Aa. Madsen, Auteur ; C. Bak, Auteur . - 2011 . - pp. [031010/1-9]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031010/1-9] Mots-clés : Aerodynamics  Noise  abatement  Noise  measurement  Optimisation  Wind  turbines Index. décimale : 621.47 Résumé : The aim of this article is twofold. First, an existing trailing edge noise model is validated by comparing with airfoil surface pressure fluctuations and far field sound pressure levels measured in three different experiments. The agreement is satisfactory in one case but poor in two other cases. Nevertheless, the model reproduces the main tendencies observed in the measurements with respect to varying flow conditions. Second, the model is implemented into an airfoil design code that is originally used for aerodynamic optimization. An existing wind turbine airfoil is optimized in order to reduce its noise emission, trying at the same time to preserve some of its aerodynamic and geometric characteristics. The new designs are characterized by less cambered airfoils and flatter suction sides. The resulting noise reductions seem to be mainly achieved by a reduction in the turbulent kinetic energy across the boundary layer near the trailing edge and to a lesser extent by a smaller boundary layer displacement thickness. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]