Abstract
Lifting surfaces produce noise in operation, and porous materials have been shown to reduce this noise. Acoustic measurements were made on three arrangements of poroelastic material: full-chord impermeability, full-chord porosity, and “mixed” porosity. The results are compared to applicable published data. The noise reduction produced by the mixed porosity arrangement is found to be similar to the fully porous arrangement at low Reynolds numbers. The noise reduction produced by the mixed and fully porous foils shows significant differences at higher Reynolds numbers. A percolation-base physical model to explain elevated noise production at high frequencies is proposed.
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Hellum, A.M. (2018). Acoustics of a Mixed Porosity Felt Airfoil. In: Ruffa, A., Toni, B. (eds) Advanced Research in Naval Engineering. STEAM-H: Science, Technology, Engineering, Agriculture, Mathematics & Health. Springer, Cham. https://doi.org/10.1007/978-3-319-95117-1_2
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DOI: https://doi.org/10.1007/978-3-319-95117-1_2
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