Effects of Airfoil Trailing Edge Thickness on the Generation of Secondary Tones
Giorgio SANTANATOGLIA, Richard D. SANDBERG, Elnaz HAJIZADEH
Abstract. New noise regulations are issued to respond to the expected impact of a massive exploitation of drones in the urban environment. The small size and low flight speed of drones is related to flight regimes characterised by low Reynolds numbers with ignorable compressibility effects. This has recently raised interest in the study of noise generated by transitional airfoils at moderate angles of attack. Where distinct narrow-band frequency peaks, which are perceived as a pitching sound over the broadband noise, are known to arise. Therefore, raising concerns in the design of quieter drones. The current research studies the effects of the airfoil trailing edge thickness on the generation of secondary tones. The flow around a NACA 0012 airfoil and the associated acoustic signature are studied with 2D DNS for six different values of the airfoil trailing edge thickness at “Re=2.0×” 〖”10″ 〗^”5″ , “Ma=0.1” , “AoA=2.0°” . The role played by the trailing edge thickness in establishing a reattachment region downstream of the laminar separation bubble on the airfoil pressure side is shown. For the first time it is demonstrated that the presence of such reattachment region just upstream of the airfoil trailing edge leads to non-negligible differences in the airfoil acoustic signature. Furthermore, an existing acoustic sharpness criterion is revised considering the presence of the reattachment region. Finally, the fluid dynamics behind the generation of the side tones is described.
Keywords
Aeroacoustics, Computational Methods, Boundary Layer Separation, Vortex Shedding
Published online 7/20/2026, 7 pages
Copyright © 2026 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Giorgio SANTANATOGLIA, Richard D. SANDBERG, Elnaz HAJIZADEH, Effects of Airfoil Trailing Edge Thickness on the Generation of Secondary Tones, Materials Research Proceedings, Vol. 69, pp 112-118, 2026
DOI: https://doi.org/10.21741/9781644904251-20
The article was published as article 20 of the book CEAS – AIDAA Conference 2025
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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