How owls could help make wind turbines and planes quieter

Researchers from Cambridge University, in collaboration with Virginia Tech, Lehigh and Florida Atlantic Universities, have studied how owls fly and hunt in silence to develop a prototype coating for wind turbine blades that could reduce the amount of noise they make.

The researchers examined owl flight feathers in fine detail and found that they have a downy covering, a flexible comb of evenly-spaced bristles along their leading edge, and a porous, elastic fringe on the trailing edge.

In order to replicate this structure, the researchers looked to design a covering that would 'scatter' the sound generated by a turbine blade in the same way the owl wing does. Early experiments included a material similar to that used for wedding veils, which lowered surface noise by as much as 30dB. However, this material was found to be unsuitable for applying to a wind turbines or aeroplanes.

The researchers then developed a prototype material made of 3D-printed plastic and tested it on a full-sized segment of a wind turbine blade. In wind tunnel tests, the treatment reduced the noise generated by 10dB, without any appreciable impact on aerodynamics. The next step is to test the coating on a functioning wind turbine.

The addition of this surface to wind turbines would mean that they could be run at higher speeds - producing more energy while making less noise. For an average-sized wind farm, this could mean several additional megawatts worth of electricity. Their results will be presented at the American Institute of Aeronautics and Astronautics Aeroacoustics Conference in Dallas on 22nd June.

Close-up of an owl's feather

Tom Austin-Morgan

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