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INM paper featured on the cover page of Physics of Fluids

The paper “The acoustic signature of a propeller–hydrofoil system in the far field”, co-authored by Drs. Antonio Posa, Riccardo Broglia and Mario Felli from CNR-INM and Prof. Elias Balaras from The George Washington University, was featured on the cover page of Physics of Fluids and published on the home page of the journal.

Results of high-fidelity, Large Eddy Simulations and the acoustic analogy were utilized to reconstruct the acoustic signature of a propeller-hydrofoil system. A number of 64,800 hydrophones, placed at 400 diameters from the propeller, was exploited to provide a detailed representation of the directivity of the sound in the far field. The study demonstrates that the acoustic signature is dominated by its loading component from the surface of both propeller and hydrofoil. At the blade frequency and higher frequencies the sound from the propeller is the leading one, especially in the upstream and downstream directions. However, at smaller frequencies the sound radiated from the hydrofoil gains the lead, especially in the directions orthogonal to its surface on the port and starboard sides. Minima of acoustic pressure always correlate with the spanwise direction of the hydrofoil. Despite the significant separation phenomena affecting the suction side of the hydrofoil at large incidence angles, no substantial increase of the sound pressure levels was found, suggesting a limited influence in the range of the lowest frequencies of the acoustic signature of the system.

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