Experimental investigation of noise generated by turbulence in a pipe flow behind a discontinuous area enlargement
Abstract
Plane sound waves and higher acoustic modes, generated by turbulence occurring in the flow separation region downstream of a discontinuous enlargement in the circular cross-sectional area of a pipe, were investigated. Measurements of the axial phase velocity of pressure fluctuations show that turbulence fluctuations dominate in the region of flow separation just behind the jump in cross-sectional area, whereas further downstream the field is primarily determined by fluctuations of the aerodynamically generated sound waves. A decomposition of the pressure fluctuations shows that in the mixing region of the jet, the fluctuation energy is primarily distributed among several azimuthal components, while further downstream almost all the energy in the frequency range below the cut-off frequency of the first higher-order mode is concentrated in the axially symmetric component.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- November 1985
- Bibcode:
- 1985PhDT........59S
- Keywords:
-
- Aerodynamic Noise;
- Pipe Flow;
- Sound Waves;
- Turbulent Flow;
- Phase Velocity;
- Plane Waves;
- Separated Flow;
- Wall Pressure;
- Fluid Mechanics and Heat Transfer