The significance of edge diffraction in sonic boom propagation within urban environments

Abstract

Advances in aircraft design, computational fluid dynamics, and sonic boom propagation modeling suggest that commercial supersonic aircraft can be designed to produce quiet sonic booms. Driven by these advances the decades-long government ban on overland supersonic commercial air transportation may be lifted. The ban would be replaced with a noise-based certification standard, the development of which requires knowledge of community response to quiet sonic booms. For inner city environments the estimation of community exposure to sonic booms is challenging due to the complex topography created by buildings, the large spatial extent and the required frequency range. Such analyses are currently intractable for traditional wave-based numerical methods such as the Boundary Element Method. Numerical methods based upon geometrical acoustics show promise, however edge diffraction is not inherent in geometrical acoustics and may be significant. This presentation shall discuss an initial investigation into the relative importance of edge diffraction in inner city sound fields caused by sonic booms. Results will provide insight on the degree to which edge diffraction effects are necessary for accurate predictions of inner city community exposure.