The nature of aircraft engine fan generated noise is described in terms of both spectral and radiative properties both statically and, where possible, in flight. Basic concepts and theoretical approaches are considered, including dimensional analysis, and thus features of the sources deduced. It is found that fans produce both tonal and random noise. While the sources of the tonal noise are several, they can be defined quite specifically, and consist mainly of regular lift fluctuations created on individual blades by inflowing distortions. For the exceptional case of supersonic relative velocity, the tonal noise is dominated by the steady pressure field relative to the blade row becoming at high supersonic speeds, a shockwave-expansion pattern. The significant sources of broad band noise are less well defined but could be produced equally well by self-excited phenomena on blade rows.
- AGARD Lecture Series, Aerodynamic Noise, at von Karman Inst Meet, Rhode St., Genese, Belgium, December 6-9, 1976.
Advisory Group Aerospace Research and Development7 Rue Ancelle
92 Neuilly-sur-Seine, France
- Lowrie, B W
- Publication Date: 1977-1
- Features: References;
- Pagination: 21 p.
- TRT Terms: Aircraft; Dimensional analysis; Distortion (Structures); Engines; Fans; Jet engines; Noise; Noise sources; Sound level; Supersonic aircraft
- Uncontrolled Terms: Aircraft engines
- Old TRIS Terms: Distortion; Fan noise; Noise generation
- Subject Areas: Aviation; Environment; Vehicles and Equipment;
- Accession Number: 00172757
- Record Type: Publication
- Source Agency: Engineering Index
- Report/Paper Numbers: No. 80, Paper 5
- Files: TRIS
- Created Date: Apr 12 1978 12:00AM