Sound Diffraction Modeling of Rotorcraft Noise Around Terrain (original) (raw)

2017

Abstract

A new computational technique, Wave Confinement (WC), is ext ended here to account for sound diffraction around arbitrary terrain. While diffraction around elementary sc attering objects, such as a knife edge, single slit, disc, sp here, etc. has been studied for several decades, realistic enviro nments still pose significant problems. This new technique is first validated against Sommerfeld’s classical problem o f diffraction due to a knife edge. This is followed by comparisons with diffraction over three-dimensional smoo th bstacles, such as a disc and Gaussian hill. Finally, comparisons with flight test acoustics data measured behind a hill are also shown. Comparison between experiment and Wave Confinement prediction demonstrates that a Poisson spot occurred behind the isolated hill, resulting in significantly increased sound intensity near the center of t he shadowed region.

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