The role of Helmholtz number in jet noise
Abstract
By using the Helmholtz number to explore the characteristics of radiated noise, it is found that both excited jets and unexcited jets behave similarly. Qualitatively a high Helmholtz number corresponds to an increased broadband level and a low Helmholtz number corresponds to a decreased broadband level. This Helmholtz number is interpreted in terms of axisymmetric and helical structures and small scale turbulence. It is a function of both Reynolds number and Mach number. In particular, the Mach number plays an important role in the turbulence dynamics of a jet; it is not just a scaling factor for acoustic efficiency.
- Publication:
-
AIAA, Aerospace Sciences Meeting
- Pub Date:
- January 1984
- Bibcode:
- 1984aiaa.meetT....L
- Keywords:
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- Aeroacoustics;
- Aerodynamic Noise;
- Dimensionless Numbers;
- Jet Flow;
- Turbulent Jets;
- Low Reynolds Number;
- Mach Number;
- Noise Spectra;
- Strouhal Number;
- Acoustics