On the use of Tailored Permeable Surfaces for Turbulence Interaction Noise Control

Turbulence interaction noise reduction using porous leading edges has been investigated experimentally. The effect of having a porous leading edge on the aeroacoustic characteristics of an additive manufactured NACA 0012 profile were investigated using leading edges manufactured from commercial metal foams and leading edges which are additive manufactured at a Reynolds number of 2.6 x 10^5. The first 10% of the airfoil is interchangeable with the multiple porous cases tested. The additive manufactured NACA 0012 profile shows a good agreement between experimental pressure coefficient values and XFoil predictions, and the interaction noise radiates well above the background of the jet. The turbulent inflow is generated by a grid placed within the contraction nozzle. The effect of the investigated leading edges are quantified in terms of the radiated far-field noise and are compared to the results of a solid leading edge. It showed that far-field noise was reduced for low frequency in all cases, although some suffer a larger high frequency penalty than others. A porous leading edge with a cover appears to abate this increase in high frequency noise and show little detrimental effect to the hydrodynamic field of the solid part of the airfoil at low angles of attack.