Low-Noise Design of Axial Fans Through Optimized Spanwise Application of Leading Edge Serrations

  • Recent studies have shown that leading edge serrations can effectively reduce broadband noise in axial fans and expand their operational range. However, additional aerodynamic losses have to be considered alongside the benefits of improved acoustic performance. The majority of studies focused on applying leading edge serrations along the entire span of the rotor blades regardless of local differences in radial inflow angles, deflection effects, and blade loading. In this regard, local and spanwise varying applications of leading edge serrations are considered crucial to reconciling maximum aeroacoustic and aerodynamic performance. In making these applications, a fan blade span is divided into five sub-segments. Each segment can then be equipped with either an acoustic or aerodynamic optimum as well as a baseline straight leading edge. Through testing at three different inflow turbulence levels along the full characteristic curve, an extensive statistical experimental design is executed. Ultimately, a simplified statistical model isRecent studies have shown that leading edge serrations can effectively reduce broadband noise in axial fans and expand their operational range. However, additional aerodynamic losses have to be considered alongside the benefits of improved acoustic performance. The majority of studies focused on applying leading edge serrations along the entire span of the rotor blades regardless of local differences in radial inflow angles, deflection effects, and blade loading. In this regard, local and spanwise varying applications of leading edge serrations are considered crucial to reconciling maximum aeroacoustic and aerodynamic performance. In making these applications, a fan blade span is divided into five sub-segments. Each segment can then be equipped with either an acoustic or aerodynamic optimum as well as a baseline straight leading edge. Through testing at three different inflow turbulence levels along the full characteristic curve, an extensive statistical experimental design is executed. Ultimately, a simplified statistical model is derived. The model provides information on the optimum spanwise shape of a serration design. The results indicate significant effects of the local spanwise selection of varying serration designs. Discrepancies between aerodynamic and aeroacoustic optimum solutions can be satisfactorily resolved where, primarily, a significant extension of the working area is observed. Moreover, an extended potential in the delay of stall entry and the associated improvement of total pressure as well as a significant reduction of aeroacoustic signature is found. The underlying mechanisms are attributed to the compartmentalization effects of the serrations which restrict separation phenomena to local cells of finite spanwise extension. Furthermore, the spanwise geometrical parametrization of the serration segments correlates well with radial blade loading as well as respective flow conditions. By taking the radial distribution of aerodynamic quantities into account, an individual design of locally applied leading edge serrations can be integrated into the fan design process, enabling improved balancing between aeroacoustic benefits while maximizing aerodynamic performance.show moreshow less

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Metadaten
Author:Alexander Felker, Till M. BiedermannORCiD, Frank Kameier
DOI:https://doi.org/10.1115/GT2023-102629
ISBN:978-0-7918-8699-1
Parent Title (English):ASME Turbo Expo 2023, Vol. 6: Education; Electric Power; Energy Storage; Fans and Blowers
Publisher:American Society of Mechanical Engineers
Document Type:conference proceeding (article)
Language:English
Date of first Publication:2023/09/28
Reviewed:Begutachtet/Reviewed
Release Date:2024/08/07
Tag:fan noise, axial fan design, aeroacoustics, leading edge serrations, experimental
Article Number:GT2023-102629, V006T10A004
Pagenumber:13
Konferenzangabe:ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition June 26–30, 2023 Boston, Massachusetts, USA
institutes:Fakultät Maschinenbau und Versorgungstechnik
Research Themes:Energie & Ressourcen
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