Attenuation of Cavity Bay Noise
Final rept. 1 Sep 2011-31 Aug 2012
CRANFIELD UNIV (UNITED KINGDOM) SCHOOL OF ENGINEERING
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This report concludes the investigation into the attenuation of cavity bay noise conducted under EOARD Award number FA8655-11-1-3025. A preliminary report was provided to EOARD in April 2012 and can be considered in conjunction with this final report. This investigation covers the experimental analysis and the development of passive palliative devices at both 140th and 120th scale and under both subsonic and supersonic conditions. Two methods of attenuation are of interest. The first is a resonant array based on the principle similar to that of a Helmholtz resonator and the second is a device comprised of a porous wire mesh coupled with a confined backing volume. The resonant arrays provide a source of viscous losses which can be targeted at the frequencies of the Rossiter modes within the cavity and the porous mesh devices provide viscous losses over a broader range of frequencies.