To reduce the aerodynamic noise of horizontal axis wind turbine blade, inspired by the quiet flight ability of owls, the asymmetric sawtooth structure of owl wing feather was been extracted and reconstructed for the trailing edge of wind turbine blade. Large eddy simulation （LES） and FW-H equation were used to analyze the flow field and sound field characteristics of the modified blade and the prototype blade. Meanwhile, the noise reduction efficiency of the blade with asymmetric sawtooth trailing edge under different structural parameters were explored. The changing structural parameters include sawtooth angle, sawtooth width and sawtooth space. The results show that the asymmetric sawtooth trailing edge has excellent effect on noise reduction, especially in the low and intermediate frequency regions. The overall sound pressure level can be reduced by 10 dB at most. When the sawtooth angle is 30°, 40° and 50°, with the increase of the sawtooth angle, the sound pressure level shows an increasing trend in most azimuth angles. When the sawtooth width is 10mm, 12.5 mm and 15 mm, with the increase of the saw tooth width, the sound pressure level decreases significantly in most azimuths. The change of saw tooth spacing has a significant impact on the noise sound pressure level at 0°azimuth angle. From the vortex distribution, it can be found that the asymmetric sawtooth trailing edge does not change the position of vortex shedding on the blade surface, but it will reduce the vortex structure and vortex intensity, increase the vortex spacing, so as to suppress the generation of noise.
Key words
aeroacoustics /
wind turbine /
blades /
bionics /
asymmetric sawtooth trailing edge /
computational fluid dynamics
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