Statistical sources for broadband shock-associated noise using the Navier-Stokes equations

Area of Science:

• Fluid Dynamics
• Aeroacoustics
• Computational Fluid Dynamics

Background:

• Broadband shock-associated noise (BBSAN) is a significant noise source in supersonic jets.
• Predicting BBSAN accurately is crucial for noise reduction strategies in aerospace applications.

Purpose of the Study:

• To identify the equivalent source term for BBSAN within the Navier-Stokes equations.
• To develop an analytical model for predicting BBSAN using an acoustic analogy.
• To validate the model against experimental data and identify noise source locations.

Main Methods:

• Decomposition of Navier-Stokes equations to isolate the BBSAN source term.
• Development of a closed-form analytical model based on acoustic analogy.
• Convolution of vector Green's function with cross-correlation of aerodynamic quantities.
• Comparison of source term scaling with experimental data and Reynolds-averaged Navier-Stokes solutions.

Main Results:

• An equivalent source term for BBSAN was identified within the Navier-Stokes equations.
• The developed analytical model shows favorable agreement with experimental BBSAN predictions.
• Source locations responsible for BBSAN at various Strouhal numbers were identified.

Conclusions:

• The study successfully identified the physical mechanism and equivalent source of BBSAN.
• The validated analytical model provides a powerful tool for predicting and mitigating jet engine noise.
• This research contributes to a deeper understanding of aeroacoustic phenomena in supersonic flows.