Design and Wind-Tunnel Verification of Low-Noise Airfoils for Wind Turbines
Th. Lutz, A. Herrig, W. Würz, M. Kamruzzaman, E. Krämer
AIAA Journal, Vol. 45, No. 4, April 2007
In this paper a method for the prediction of the airfoil trailing-edge far-field noise is presented. The model comprises the panel boundary-layer code XFOIL to determine the initial and boundary-conditions for a subsequent analysis using the Finite-Difference code EDDYBL featuring a Reynolds stress turbulence model that finally provides the input data for the noise prediction by a modified TNO-TPD model. The prediction scheme was applied in the frame of the European SIROCCO project to design new, less-noisy airfoils for the outer blade region of three different wind turbines in the MW class. The objective was to reduce the total sound pressure level without loss in aerodynamic performance. Wind tunnel tests showed that a noticeable noise reduction could be achieved compared to the airfoils used so far. Moreover, the aerodynamic performance could be improved in the design region as well.