Issue |
Acta Acust.
Volume 6, 2022
Topical Issue - Aeroacoustics: state of art and future trends
|
|
---|---|---|
Article Number | 48 | |
Number of page(s) | 12 | |
DOI | https://doi.org/10.1051/aacus/2022043 | |
Published online | 25 October 2022 |
Scientific Article
Aerodynamic and aeroacoustic properties of axial fan blades with slitted leading edges
1
Aalen University of Applied Sciences, Institute for Virtual Product Development, Beethovenstr. 1, 73430 Aalen, Germany
2
Friedrich-Alexander University Erlangen-Nuremberg, Institute for Fluid Mechanics, Cauerstr. 4, 91058 Erlangen, Germany
3
University of Southampton, Institute of Sound and Vibration Research, University Road, Southampton SO17 1BJ, UK
4
Aalen University of Applied Sciences, Mechanical Engineering and Materials Science, Beethovenstr. 1, 73430 Aalen, Germany
* Corresponding author: christof.ocker@hs-aalen.de
Received:
3
March
2022
Accepted:
26
September
2022
A detailed experimental analysis of the aerodynamic and aeroacoustic properties of flat-plate axial fans with slitted leading edges is performed. The sound emissions of five slitted leading edge designs are measured at a constant rotational speed and at a constant total-to-static pressure rise of the fans. For both cases, the fan blades with slitted leading edges reduce the turbulence interaction noise and lead to a reduction of the overall sound pressure level for volume flow rates above 0.6 m3 s−1 compared to an axial fan with solid leading edges. The far-field noise analysis shows that the slits result in a noise reduction for frequencies below 2 kHz and a noise increase above 2 kHz. In addition, sound source localization is conducted with a microphone array and rotating beamforming methods are applied. The identified sound source distributions prove that slitted leading edges reduce turbulence interaction noise, but generate broadband noise in the fan blades’ trailing edge regions. The maximum sound reduction due to the slits could be detected at a dimensionless frequency of , where f is the frequency, h is the height of the slit and is the mean relative inflow velocity. The noise reduction mechanism on axial fan blades corresponds well to previous investigations on flat-plate airfoils with slits.
Key words: Slitted leading edges / Turbulence interaction noise / Noise reduction / Microphone array / Rotating beamforming / Axial fan
© The Author(s), Published by EDP Sciences, 2022
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