Wind tunnel Investigation on Trailing Edge Noise Mitigation via Sawtooth Serrations

Engler Faleiros, D. (2015) Wind tunnel Investigation on Trailing Edge Noise Mitigation via Sawtooth Serrations.

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Abstract:Problem area Wind turbines noise production due to the interaction of the blades and the air. Description of work This report investigates the performance of sawtooth serrations in mitigating trailing edge noise from a DU-96-W-180 airfoil section, which is designed especially for wind turbines. The experiments were realized at NLR’s Open-Jet Anechoic KAT wind tunnel. Acoustic measurements were performed with a 48-microphone array. Aerodynamic experiments were done via hot-wire traverses to obtain the boundary-layer and wake parameters. Results and conclusions Suction side mounted serrations gave higher noise reductions than pressure side mounted serrations. The hypothesis is that the interaction of the thin boundary-layer on the pressure side with the step caused by the thickness of the serration generates additional spurious noise. Serrations, in general, decrease the aerodynamic efficiency and the pros and cons of using it need to be taken into account when considering full scale application. Applicability Serrations can be applied on wind turbine blades to decrease airfoil self-noise that occurs due to boundary-layer turbulence that passes over the trailing edge. This is the main noise mechanism of wind turbines, considering everything else is adequately treated. Decreasing the noise from the blades would enable to install more wind turbines close to urban areas and open the possibility for harvesting sustainable energy. Furthermore, serrations can also be applied in airplane wings to help reduce the noise during the landing phase. Nevertheless, this application is not considered to be the focus of this report.
Item Type:Internship Report (Master)
Clients:
NLR, the Netherlands
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Sustainable Energy Technology MSc (60443)
Keywords:Serrations, Trailing Edge Noise, Wind tunnel, Acoustics
Link to this item:http://purl.utwente.nl/essays/69902
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