Jet noise reduction using porous materials
L. (Leandro) Rêgo
Dr. D. (Daniele) Ragni
Associate Professor
Dr. F. (Francesco) Avallone
Assistant Professor
The progressive increase of the bypass ratio of turbofan engines has resulted in a closer coupling between engine and lifting surfaces; as the engines become larger, their distance from the wing needs to be reduced in order to ensure a minimum ground clearance. This results in interactions between the jet and wing, causing noise amplification (jet-installation noise), particularly if high-lift devices are deployed. Therefore, installation effects have to be mitigated in order for future aircraft to fulfill ever more stringent noise certification requirements.
A possible solution for jet-installation noise reduction is the application of porous materials on the airframe surface near the trailing-edge. Similar concepts have been investigated, but for different applications, such as flap side-edge noise and airfoil turbulent boundary-layer trailing-edge noise with encouraging results. The use of porous materials results in lower surface pressure fluctuations and, consequently, lower noise at the far-field. However, care must be taken in order to avoid lift decrease and drag augmentation. Therefore, the goal of the research is to develop solutions based on porous materials for aircraft applications, focusing on jet-installation noise, which
provide significant acoustic benefits, with a minimum effect on the aircraft performance.
Sound waves generated at the flap trailing edge
Rego, L., Casalino, D., Avallone, F. and Ragni, D., 2019. Noise Amplification Effects due to Jet-Surface Interaction. In AIAA Scitech 2019 Forum (p. 0001). DOI: 10.2514/6.2019-0001
Rego, L.F., Avallone, F., Ragni, D., Casalino, D. and van der Velden, W.C., 2019. Free-Stream Effects on Jet-Installation Noise of a Dual-Stream Engine. In 25th AIAA/CEAS Aeroacoustics Conference (p. 2491). DOI: 10.2514/6.2019-2491
Rego, L., Avallone, F., Ragni, D. and Casalino, D., 2020. Jet-installation noise and near-field characteristics of jet–surface interaction. Journal of Fluid Mechanics, 895. DOI: 10.1017/jfm.2020.294
Leandro has a Bachelor degree in Aeronautical Engineering and a MSc in Mechanical Engineering from the University of Sao Paulo in Brazil. He is currently a PhD candidate at the Delft University of Technology, working on jet aeroacoustics and jet-installation noise reduction through the application of porous materials.
Daniele Ragni graduated in Thermo-Mechanical Engineering at the Polytechnic University of Marche (2007). Obtained the Ph.D. in 2012 (Faculty of Aerospace Engineering TU Delft) and joined TU Delft at the section of Wind Energy in the AWEP Department in the same year.
Francesco Avallone studied Aerospace Engineering at the University of Naples Federico II where he obtained also the PhD. His research interest focus on application of computational aeroacoustics to investigate the noise generation mechanisms and noise reduction solutions for wind energy and aeronautical applications. He is currently working on acoustic liners, porous materials and urban wind turbines on projects sponsored by Clean Sky 2, NWO and AARC.