On the application of acoustic liners for the reduction of jet-flap installation noise

• Published in: Applied acoustics 2024-05, Vol.221, p.110029, Article 110029
• Main Authors: Sirotto, José R.L.N., Bonomo, Lucas A., Cordioli, Julio A.
• Format: Article
• Language: English
• Subjects: Acoustic liners; Boundary element method; Installed jet noise; Jet noise
• ISSN: 0003-682X; 1872-910X
• DOI: 10.1016/j.apacoust.2024.110029

In this work, an experimental and numerical analysis of the feasibility of using acoustic liners to reduce the acoustic far-field radiation of a subsonic jet near a flat plate is presented. The Boundary Element Method (BEM) with a wavepacket model of the jet noise and considering an acoustic impedance boundary condition was used to calculate the far-field noise for different conditions. A parametric optimization was performed in order to find an optimum impedance in terms of the Overall Sound Pressure Level reduction. Semi-empirical models of acoustic liners were then used to design a liner with an impedance as close as possible to the optimum impedance. The liners were built using additive manufacturing and tested in terms of their acoustic impedance and the resulting noise reduction when applied to a region of the flat plate. The BEM simulations, considering the impedance, showed good agreement with experimental data. Overall, by means of the BEM model, optimization and liner semi-empirical models, it was possible to design an acoustic liner which significantly reduced the installation noise at the far-field, with the overall noise reduction between 2 dB to 4 dB depending on observation angle. •The BEM method is used to predict the acoustic field of installed jet noise.•The numerical tool is used to investigate lining the surface close to the jet.•Results suggest that the numerical tool is able to predict the noise attenuation.