Owl wing design can limit noise from wind turbines and planes

Noise pollution is more than annoying. Research has shown its impact on fish, songbirds and human health as well. But nature itself may offer a solution, and scientists in China report that designs based on how owl wings work could have the potential to reduce aircraft noise.

It’s not just planes either. The same principle could work for drones and other unmanned aerial vehicles, as well as wind turbines.

“Night owls produce about 18 decibels less noise than other birds at similar flight speeds due to their unique wing configuration,” says lead author Xiaomin Liu of Xi’an Jiaotong University. “Furthermore, when the owl captures prey, the shape of the wings is also constantly changing, so the study of the wing edge configuration during the owl’s flight is of great importance.”

The findings, published Tuesday in the journal Physics orf Fluids , they are based on models that scientists have used to assess what is known as trailing edge noise. Occurs when air flows through the back of an airfoil. This causes air turbulence on the top and bottom surfaces of the blade or other “wing” structure.

This is the dominant sound people hear from aircraft engines. It’s also what many cities want to reduce; the authors point out that London’s Heathrow airport, for example, imposes fines on aircraft carriers when its strict nighttime noise rules are violated.

For a long time it was difficult to find a successful solution

There have been some improvements when serrated teeth are used on rotating machines, but it is not consistent from one location or system to another.

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“The design of turbomachinery rotating blades has gradually matured, but noise reduction technology is still at a bottleneck,” says Liu. “The noise reduction capabilities of conventional sawtooth structures are limited, and some new non-smooth trailing edge structures need to be proposed and developed.”

There is still more work to be done, but the noise calculations and analysis done on the owl-wing-based designs are promising. One finding, for example, is that an asymmetrical design reduces noise more than symmetrical ones.

Yet machines like the wind turbines operate in complicated airflow dynamics. It is not yet known how noise reduction techniques work in a variety of different airflows.

On the other hand, the owl in flight also works as a rather complicated “machine”. Owls maneuver in low-speed, silent glides while maintaining stability, all based on factors including complex airflows and aerodynamic principles.

“The silent flight of owls is based on the coupling effect of several factors,” the authors write. “These multiple factors deserve specific attention, rather than duplicating a single coupling element, to further design silent rotating machines and micro-aerial vehicles.”

By Lauren Fagan. Article in English

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