Those of us near highways and airports live with menacing air and noise pollution every day. High-speed aircraft, in particular, contribute to a constant roar in our air, but that might soon change. The inspiration for change comes from an animal synonymous with wisdom: the owl.
Unique among birds, owls represent the stealthiest of our winged friends. By flying quietly, they can snatch unsuspecting prey even in the dead of night. The downy canopy that the owl grows on the top of its wing allows silent flight. By studying the structure of that downy layer, scientists constructed a similar airfoil attachment that reduces wind turbine noise by 10 decibels. This could translate to a significant drop in noise pollution.
A Natural Defense Against Noise Pollution
Researchers from Lehigh University, Virginia Tech, Florida Atlantic University and the University of Cambridge collaborated to create the new, owl-inspired wing canopy. Looking at large owl wings under a microscope, they found that the downy layer atop their wings consists of small hairs that resemble a forest with a mature canopy.
“Using this design, scientists created an attachment for an airfoil, which effectively reproduces the effect of the owl’s own downy canopy above the wing.”
Scientists even improved the silencing effect by removing any cross-fibers from the downy canopy. Removing the cross-fibers allows air to flow along the wing in a single direction, cutting down the noise generated while flying.
Using this design, scientists created an attachment for an airfoil, which effectively reproduces the effect of the owl’s own downy canopy above the wing. According to Lehigh Assistant Professor Justin W. Jaworski, “The canopy of the owl wing surface pushes off the noisy flow. Our design mimics that but without the cross fibers, creating a unidirectional fence – essentially going one better than the owl.”
This Brings a Welcome Silence
The attachment can be retro-fitted to an existing wing, and should not conflict with other noise dampening measures. The implications of this technology are promising, as noise pollution from airports is a very real concern that has manifested as legal regulation.
Supersonic aircraft such as the Concorde and NASA’s future X-planes may also benefit, as an inability to quiet the sonic boom has hampered the development of commercial supersonic travel. The attachment wouldn’t totally solve the problem, but it could contribute to an eventual solution for supersonic noise pollution.
At our next opportunity, we will thank the owl for our quieter airspace.