Numerical Investigation of Acoustic Noise of an Oscillating NACA0012 Airfoil Equipped with Triangular javascript:goStep(3)Serrations

Document Type : Research Article

Authors

Department of Aerospace Engineering, Amirkabir University of Technology, Tehran, Iran

Abstract

Aerodynamic noise generated by airfoils poses a serious industrial challenge because of its detrimental impact on human hearing and on the performance of vehicles and wind turbines. This noise rooted in geometric parameters, vortex shedding and flow separation can be mitigated by mounting triangular serrations on the trailing edge. In the present study, the aeroacoustic behaviour of an oscillating NACA 0012 airfoil with a ±10° pitching amplitude and oscillation frequencies between 5 and 25 Hz about its aerodynamic center was evaluated numerically. The flow field was solved with the Unsteady Reynolds-averaged Navier–Stokes equations with the k-ω SST turbulence model, while the surrounding acoustic field was predicted through the Ffowcs Williams–

Hawkings (FW-H) acoustic analogy. Acoustic metrics, including sound pressure level and power spectral density,

were recorded at several downstream positions from the trailing edge. results demonstrate that the serrations

fragmented large scale vortices into smaller structures and, on average, lowered vortex-induced noise by 4.58 dB from 51.18 dB equivalent to a 8.95% reduction. This attenuation is attributed to weakened dominant vortices, reduced velocity fluctuations and creating phase shifts in acoustic wave propagation, which collectively suppress

wake turbulence and limit acoustic energy propagation, thereby enhancing aeroacoustic performance. The

effectiveness of serrations was frequency dependent, exhibiting greater efficacy at lower oscillation frequencies and reduced effectiveness at higher frequencies due to intensified flow instabilities.

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Amirkabir Journal of Mechanical Engineering
Volume 57, Issue 3
June 2025
Pages 303-332

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