Shallow surface-wave simulator for the study of jet-noise sources
Abstract
A shallow liquid surface-wave analogy to turbulence-induced sound was utilized to investigate the mechanisms of noise generation and propagation in jets. Theoretical analysis was used to determine the wave-power dependence on Mach number and to derive the relationship between wave and turbulence spectra. The experimental investigation utilized a 24-sq ft mercury ripple tank. The waves were produced by the turbulence in a mercury jet exhausting into the tank. The results substantiate the validity of the surface-wave analogy as a jet-noise simulator. Measurement of mean and turbulent velocity profiles proved that the jet development was similar to the theoretical plane-free jet. Far-field measurements of wave power, directivity, and spectra compared favorably with the acoustic case. However, the wave spectra showed little of the higher-frequency content found in the turbulence spectra. This difference was attributed to the vertical spatial integration of the turbulence-source terms, which is not found in jet noise.
- Publication:
-
Acoustical Society of America Journal
- Pub Date:
- July 1977
- DOI:
- 10.1121/1.381492
- Bibcode:
- 1977ASAJ...62..117C
- Keywords:
-
- Acoustic Simulation;
- Jet Aircraft Noise;
- Liquid Surfaces;
- Noise Generators;
- Noise Propagation;
- Surface Acoustic Wave Devices;
- Far Fields;
- Free Jets;
- Mach Number;
- Noise Measurement;
- Noise Spectra;
- Power Spectra;
- Propagation Velocity;
- Turbulence Effects;
- Two Dimensional Jets;
- Velocity Distribution;
- Acoustics