APPLICATIONS OF DIFFRACTION THEORY TO AEROACOUSTICS
A review is given of the fundamentals of diffraction theory and the application of the theory to several problems of aircraft noise generation, propagation, and measurement. The general acoustic diffraction problem is defined and the governing equations set down. Diffraction phenomena are illustrated using the classical problem of the diffraction of a plane wave by a half-plane. Infinite series and geometric acoustic methods for solving diffraction problems are described. Four applications of diffraction theory are discussed: the selection of an appropriate shape for a microphone, the use of aircraft wings to shield the community from engine noise, the reflection of engine noise from an aircraft fuselage and the radiation of trailing edge noise.
- Presented at the Vki/AGARD Special Course, Brussels, 28 May-1 June 1979.
Langley Research CenterNational Aeronautics and Space Administration
Hampton, VA USA 23665
- Lansing, D L
- Chen-Huei, L
- Norum, T D
- Publication Date: 1979-1
- Pagination: 14 p.
- TRT Terms: Acoustic scattering; Aerodynamic noise; Aircraft noise; Diffraction; Electromagnetic radiation; Measurement; Microphones; Noise; Noise generators; Numerical analysis; Plane waves; Reflection; Sound; Sound; Wave motion; Wings (Aircraft)
- Uncontrolled Terms: Aircraft engines; Noise measurement
- Old TRIS Terms: Aeroacoustics; Wave diffraction
- Subject Areas: Aviation; Environment; Vehicles and Equipment;
- Accession Number: 00192315
- Record Type: Publication
- Source Agency: National Technical Information Service
- Report/Paper Numbers: NASA-TM-80053
- Files: TRIS
- Created Date: Jul 31 1979 12:00AM