Noise emission and propagation in an air flow
Abstract
Sound propagation from a jet engine on an aircraft moving at a constant airspeed is examined in terms of the turbulent field, the near field, and the far field. The near and far fields are irrotational disturbances of a permanently adiabatic flow for which the entropy and enthalpy are the critical parameters. The propagation velocity of the noise is formulated, together with the extent of the acoustic field. The acoustic excitation is shown to dominate the extent of the acoustic field, while the pseudo-noise and the sound density are equal to the sound pressure and are not noise sources. The unsteady part of the turbulence noise is controlled by the pressure gradient, particularly that around the axes of the eddies.
- Publication:
-
Academie des Sciences Paris Comptes Rendus Serie Sciences Mathematiques
- Pub Date:
- January 1983
- Bibcode:
- 1983CRASM.296..229L
- Keywords:
-
- Aerodynamic Noise;
- Aircraft Noise;
- Noise Propagation;
- Air Flow;
- Propagation Velocity;
- Turbulent Flow;
- Acoustics