Aerodynamics and Aeroacoustics of Leading Edge Serration in Low-Speed Axial Fans With Forward Skewed Blades

Tieghi L, Czwielong F, Barnabei VF, Ocker C, Delibra G, Becker S, Corsini A (2024)

Publication Type: Journal article

Publication year: 2024

Journal

Journal of Engineering For Gas Turbines and Power-Transactions of the Asme American Society of Mechanical Engineers (ASME)

Book Volume: 146

Article Number: 021007

Journal Issue: 2

DOI: 10.1115/1.4063420

Abstract

Low-speed axial fans must comply with a wide number of standards and normative restrictions, often related to the maximum noise emission levels. Among the noise control techniques in axial fans, skewed fan blades and leading edge serrations have been found to be effective in leading edge noise control, which represents one of the dominant phenomena in axial fan broadband emissions. However, these solutions are usually applied separately, and literature is scarce on systematic studies on the coupling of the two modifications. In this work, a campaign of experimental measurements was conducted on unskewed and forward-skewed axial fan blades with and without leading-edge serrations. The tests were performed in undisturbed inflow conditions. The flow field and the turbulence characteristics were measured using three-dimensional hot-wire anemometry. The suction-side sound radiation of the fans was measured with microphones in an anechoic chamber. In addition, the rotating beamforming method was used to localize the sound sources at the axial fans. It was found that, regardless of the blade skew, the leading edge serrations lead to a reduction of the sound pressure level, whereby the aerodynamic properties of the fan decrease. At the same operating points, which were achieved by adjusting the rotational speed, the sound radiation through the leading edge serrations could be reduced at high-volume flows. This effect was more pronounced with the unskewed rotor, which indicates that the positive effect of the serrations is reduced by the already optimized shape of the forward skewed fan blade. Based on the experimental results, the four geometries were further considered for numerical investigations to understand how the serrations affect the fan operations and the overall aerodynamics of the rotor. All four geometries were simulated with RANS approach at the duty point to derive a flow survey and better understand the dynamics driven by serrations and blade skewing.

Authors with CRIS profile

Felix Czwielong Lehrstuhl für Strömungsmechanik (LSTM) Stefan Becker Lehrstuhl für Strömungsmechanik (LSTM)

Involved external institutions

Università degli studi "La Sapienza" IT Italy (IT) Hochschule Aalen DE Germany (DE)

How to cite

APA:

Tieghi, L., Czwielong, F., Barnabei, V.F., Ocker, C., Delibra, G., Becker, S., & Corsini, A. (2024). Aerodynamics and Aeroacoustics of Leading Edge Serration in Low-Speed Axial Fans With Forward Skewed Blades. Journal of Engineering For Gas Turbines and Power-Transactions of the Asme, 146(2). https://doi.org/10.1115/1.4063420

MLA:

Tieghi, Lorenzo, et al. "Aerodynamics and Aeroacoustics of Leading Edge Serration in Low-Speed Axial Fans With Forward Skewed Blades." Journal of Engineering For Gas Turbines and Power-Transactions of the Asme 146.2 (2024).

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