Acoustic intensity-based method for sound radiations in a uniform flow

Area of Science:

• Aeroacoustics
• Computational Fluid Dynamics (CFD)
• Computational Aeroacoustics (CAA)

Background:

• Predicting aerodynamic noise propagation is crucial for understanding sound radiation.
• Existing methods may face limitations in far-field predictions or when specific acoustic inputs are unavailable.

Purpose of the Study:

• To extend and verify an acoustic intensity-based method (AIBM) for predicting sound radiation in subsonic uniform flow.
• To couple AIBM with near-field CFD/CAA methods for enhanced aeroacoustic predictions.

Main Methods:

• The AIBM utilizes the modified Helmholtz equation with acoustic pressure and its derivative as inputs from an open control surface.
• A least squares problem is solved to obtain a unique solution for the modified Helmholtz equation.
• The method is integrated with near-field CFD/CAA simulations.

Main Results:

• The extended AIBM accurately predicts sound radiation for both tonal and broadband noise in model aeroacoustic problems.
• The hybrid CFD/CAA-AIBM approach demonstrates effectiveness in various scenarios.
• The method proves stable and accurate using acoustic data from an open surface.

Conclusions:

• The AIBM offers an advantageous approach for far-field aerodynamic noise prediction.
• It provides a viable alternative when acoustic input from closed control surfaces (e.g., Ffowcs Williams-Hawkings) is not accessible.
• The extended AIBM enhances the capability to predict sound radiation in subsonic flows.