Sharif Journal of Mechanical Engineering

Sharif Journal of Mechanical Engineering

Novel Acoustic Absorbers Based on TPMS Structures: Implementation in Axial Fan Casings and Ducted Wind Turbines

Document Type : Article

Authors
mostafa mozafari 1
Mehran Masdari 2
1 1College of Interdisciplinary Science and Technology, University of Tehran, Tehran, Iran.
2 College of Aerospace Engineering, Coventry University, United Kingdom
10.24200/j40.2026.67925.1754
Abstract
Rotating systems such as axial flow fans and wind turbines play a vital role in cooling processes and clean energy generation. However, a major challenge in their operation is the noise produced by flow instabilities, particularly tip-leakage vortices. Consequently, the development of advanced noise-reduction technologies has become an important research priority. Recent studies have demonstrated that incorporating porous casings can significantly mitigate noise levels. In this study, porous structures based on Triply Periodic Minimal Surfaces (TPMS) were employed to evaluate their aeroacoustic performance. First, the sound absorption coefficient of these structures was analyzed, and the Gyroid with 50% porosity was identified as the optimal design. This structure was then applied to two key case studies: the casing of an axial fan and the duct surrounding a ducted wind turbine. A combined numerical and experimental analysis was conducted to investigate both aerodynamic characteristics and the mechanisms of noise generation and suppression. The results indicate that the TPMS-based casing effectively reduces the strength and size of tip-leakage vortices while attenuating turbulence intensity near the casing wall. Moreover, the optimized design suppresses both blade passing frequency (BPF) noise and turbulence-interaction noise. Quantitatively, the proposed approach achieved a 6 dB reduction in OASPL (approximately 11%) for the axial-flow fan, corresponding to a 36% decrease in accumulated acoustic energy. For the ducted wind turbine, the porous structure improved acoustic behavior, leading to an 8% reduction in overall sound pressure level (OASPL). These findings confirm that TPMS-based designs offer a promising and efficient aeroacoustic solution for noise reduction in rotating machinery.
Keywords
Sound absorber
aeroacoustics
noise reduction
porous media
Subjects
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