A phenomenological approach to jet noise: the two-source model.

Area of Science:

• Aeroacoustics
• Fluid Dynamics
• Acoustics

Background:

• The two-source model of jet noise was developed phenomenologically.
• Previous research identified two similarity jet noise spectra within this model.
• Extensive comparisons with NASA spectrum data validated the model's core findings.

Purpose of the Study:

• To review the established two-source model of jet noise.
• To elaborate on the underlying flow physics, noise generation, and directivity.
• To discuss supporting experimental data and broader applicability.

Main Methods:

• Phenomenological model development.
• Extensive comparison with NASA experimental jet noise data.
• Analysis of flow physics, turbulence, and noise generation mechanisms.

Main Results:

• Identification of two universal similarity jet noise spectra.
• Demonstration that these spectra can fit measured noise in any direction, irrespective of jet conditions.
• Validation of the model with additional experimental data.

Conclusions:

• The two-source model provides a robust framework for understanding and predicting jet noise.
• The identified similarity spectra have broad applicability beyond the original dataset.
• The model's principles extend to diverse acoustic phenomena, including military jets, rockets, and volcanoes.