Trailing edge noise can be a significant source in many applications. It is produced by the scattering of convected turbulent sources by a sharp edge. We have studied conventional methods of treating trailing edge noise focused on modifications to the trailing edge geometry (e.g., serrations). More recently, we have developed a novel method of reducing trailing edge noise by treating the boundary layer (the source term) instead. This research is inspired by the silent flight of certain species of owls. These owls have a fine downy coating on their feathers that we speculate is used to attenuate the strength and reduce the spanwise correlation of turbulence in the wing boundary layer. We have adapted these fine structures as a series of near wall fins and rails which we call finlets. These features function differently than other airfoil adaptations such as riblets or wing fences. Wind tunnel experiments confirm the capability of these devices and full-scale demonstrations are being planned.
Finlets at the trailing edge of a wing