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Open AccessArticle

Experimental and Analytical Investigation of the Tonal Trailing-Edge Noise Radiated by Low Reynolds Number Aerofoils

1
Laboratoire de Mécanique des Fluides et d’Acoustique, Université de Lyon, École Centrale de Lyon, F-69134 Écully, France
2
Département de génie mécanique, Université de Sherbrooke, Sherbrooke, QC J1K2R1, Canada
3
Aerospace Engineering Department, Embry-Riddle Aeronautical University, Daytona Beach, FL 32114-3900, USA
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Acoustics 2020, 2(2), 293-329; https://doi.org/10.3390/acoustics2020018
Received: 18 March 2020 / Revised: 1 May 2020 / Accepted: 8 May 2020 / Published: 14 May 2020
An experimental and analytical study of the tonal trailing-edge noise of a symmetric NACA-0012 aerofoil and of a cambered SD7003 aerofoil has been achieved. It provides a complete experimental database for both aerofoils and improves the understanding of the underlying mechanisms. The analysis stresses the high sensitivity of the tonal noise phenomenon to the flow velocity and the angle of attack. Several regimes of the noise emission are observed depending on the aforementioned parameters. The contributions of the pressure and the suction sides are found to vary with the flow parameters too. A special attention has been paid to the role of the separation bubble in the tonal noise generation. Hot-wire measurements and flow visualization prove that the separation bubble is a necessary condition for the tonal noise production. Moreover, the bubble must be located close enough to the trailing edge. Several tests with small-scale upstream turbulence confirm the existence of the feedback loop. Analytical predictions with a classical trailing-edge noise model show a good agreement with the experimental data; they confirm the cause-to-effect relationship between the wall-pressure fluctuations and the radiated sound. Finally, previously reported works on fans and propellers are shortly re-addressed to show that the tonal noise associated with laminar-boundary-layer instabilities can take place in rotating blade technology. View Full-Text
Keywords: aerofoil noise; tonal noise; boundary-layer instability; whistling aerofoil noise; tonal noise; boundary-layer instability; whistling
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Yakhina, G.; Roger, M.; Moreau, S.; Nguyen, L.; Golubev, V. Experimental and Analytical Investigation of the Tonal Trailing-Edge Noise Radiated by Low Reynolds Number Aerofoils. Acoustics 2020, 2, 293-329.

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