Relevance of quadrupolar sound diffraction on flow-induced noise from porous-coated cylinders

This paper elucidates the link between the near-wake development of a circular cylinder coated with a porous material in a low Mach-number flow and the related aerodynamic sound attenuation. It accomplishes this by formulating the cylinder flow-induced noise as a diffraction problem. The necessity for such an approach is driven by...

On the mechanisms of jet-installation noise reduction with flow-permeable trailing edges

This paper investigates the mechanisms by which flow-permeable materials provide noise reduction in an installed jet configuration. Numerical simulations are carried out with a flat plate placed in the near field of a single-stream subsonic jet (M_a=0.3 and M_a=0.5). The trailing-edge region of the plate is replaced by...

Innovative Permeable Materials for Broadband Trailing-Edge Noise Mitigation

Permeable trailing edges are experimentally investigated in this thesis as a mean tomitigate aeroacoustic noise. The first part of the study is devoted to deciphering themechanisms of noise generation involved in these devices. To this aim, trailing-edge inserts are manufactured employing commercially-produced open-cell metallic foams with...

Jet-installation noise reduction with flow-permeable materials

This paper investigates the application of flow-permeable materials as a solution for reducing jet-installation noise. Experiments are carried out with a flat plate placed in the near field of a single-stream subsonic jet. The flat plate is modular and the solid surface near the trailing edge can be replaced with different flow-permeable...

Experimental investigation of turbulent coherent structures interacting with a porous airfoil

Abstract: The flow field on solid and porous airfoils subjected to turbulence shed by an upstream cylindrical rod and the corresponding far-field noise radiations are studied through particle image velocimetry (PIV) and microphone measurements, respectively. Three different Reynolds numbers based on the rod diameter are considered in a range...