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On the modelling of wavepacket scattering noise with coherence effects
Filipe D da Silva1, Peter Jordan2, André V G Cavalieri3
1TEG Thermofluids Engineering Group, Federal University of Santa Catarina, Joinville-Santa Catarina, 89219-600, Brazil.
The Journal of the Acoustical Society of America
|January 3, 2020
Summary
A wavepacket model accurately predicts trailing edge noise in installed jets, simplifying noise modeling. Free-jet predictions showed deviations, but installed jet noise proved less sensitive to coherence decay.
Area of Science:
- Acoustics
- Computational Fluid Dynamics (CFD)
- Aerospace Engineering
Background:
- Jet noise is a significant concern in aerospace applications.
- Understanding jet-surface interaction is crucial for noise reduction.
- Previous models struggled to accurately capture noise characteristics.
Purpose of the Study:
- To investigate a wavepacket model for free-jet and jet-surface interaction noise.
- To assess the model's performance in predicting noise directivity and source field characteristics.
- To compare noise prediction for isolated jets versus installed jets.
Main Methods:
- Utilized a Mach 0.9 jet large eddy simulation (LES) to extract the source term for the axisymmetric mode.
- Adjusted parameters of a simple source model using LES data, focusing on streamwise coherence decay.
- Propagated the source model using free-field and tailored Green's functions for jet-surface interaction.
- Analyzed noise predictions for both isolated and installed jet configurations.
Main Results:
- The wavepacket model showed significant deviations in predicting low-angle directivity for isolated jets.
- The model's reproduction of isolated jet source field characteristics was also found to deviate.
- Trailing edge noise effects were well reproduced by the model.
- The installed jet case exhibited minimal sensitivity to coherence decay in regions dominated by trailing edge scattering.
Conclusions:
- The wavepacket model simplifies installed jet noise prediction due to reduced sensitivity to coherence decay.
- The model's accuracy varies between isolated and installed jet scenarios.
- Trailing edge noise is a dominant factor well-captured by the model in installed configurations.
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