Noise reduction technologies for wind turbines

Abstract

Results from a numerical and experimental aeroacoustic assessment of 2D wind turbine blade sections are presented. CFD/CAA-based predictions using a synthetic turbulence method were conducted at a NACA 64-618 profile as well as at a new low-noise airfoil design RoH-W-18%c37. Validation experiments were performed in DLR’s Acoustic Wind-Tunnel Braunschweig (AWB) for varying transition locations. A trailing-edge noise reduction benefit of 2–4 dB in overall sound pressure level was predicted for the new airfoil under design conditions. A large laminar extent of the boundary layer significantly reduces the noise emission (by up, to 8, dB) compared to equivalent cases with forced transition at the leading edge. An additional noise reduction (with realistic reductions of the peak levels by 4–6, dB) was accomplished by flow-permeable trailing-edge extensions which were successfully transferred to the two profiles from forerunner aerospace-related studies.