Aeroacoustic Interactions of Blade Skew and Leading Edge Serrations Applied to Low-Pressure Axial Fans

  • Leading edge serrations are well known for their ability to reduce turbulence-induced noise of single aerofoils while also providing aerodynamic advantages under certain operating conditions. Continuatively, applying leading edge serrations to rotating machinery such as axial fans proved the validity to generally transfer the obtained aeroacoustic benefits of single aerofoils. However, for the rotating applications the noise reduction potential highly depends on the point of operation. The current work aims at assessing the aeroacoustic effects of serrated leading edges under the increased geometrical complexity of the fan blades through blade skew. Therefore, the question is whether combining two potentially effective noise-reducing treatments through blade skew and leading edge serrations results in leveraging or obstructing effects. By varying the skew angle from 0 deg to 38 deg, four different prototypes of the fan impeller are tested experimentally in a test rig according to ISOLeading edge serrations are well known for their ability to reduce turbulence-induced noise of single aerofoils while also providing aerodynamic advantages under certain operating conditions. Continuatively, applying leading edge serrations to rotating machinery such as axial fans proved the validity to generally transfer the obtained aeroacoustic benefits of single aerofoils. However, for the rotating applications the noise reduction potential highly depends on the point of operation. The current work aims at assessing the aeroacoustic effects of serrated leading edges under the increased geometrical complexity of the fan blades through blade skew. Therefore, the question is whether combining two potentially effective noise-reducing treatments through blade skew and leading edge serrations results in leveraging or obstructing effects. By varying the skew angle from 0 deg to 38 deg, four different prototypes of the fan impeller are tested experimentally in a test rig according to ISO 5136 and ISO 5801. All configurations are tested with original blades of straight leading edges plus five sets of serrations each, parameterised by the serration amplitude and the serrations wavelength. The intensity of the incoming turbulence ranges from 2.6% to 12.1%. The results obtained show the skewed blades to improve both the aerodynamic performance and the noise radiation after exceeding an initial skew angle, complemented by a significant onset of stall. Moreover, no contraindication between blade skew and serrated leading edges is encountered, showing the potential to further extend the noise reduction capabilities by combining effects of blade skew and leading edge treatment.show moreshow less

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Metadaten
Author:Till M. BiedermannORCiD, Nils Hintzen, Frank Kameier
Qualitätssicherung:peer reviewed
Institutes:Institute of Sound and Vibration Engineering (ISAVE)
Fachbereich/Einrichtung:Hochschule Düsseldorf / Fachbereich - Maschinenbau und Verfahrenstechnik
Document Type:Article
Year of Completion:2022
Language of Publication:English
Publisher:ASME
Parent Title (English):Journal of Engineering for Gas Turbines and Power
Volume:144
Issue:12
Article Number:121022
Page Number:12
DOI:https://doi.org/10.1115/1.4055637
ISSN:0742-4795
GND Keyword:Lärmschutz; Turbulenz; Ventilator
Licence (German):keine Lizenz - nur Metadaten
Release Date:2025/01/06
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