Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Owl-inspired wing design reduces wind turbine noise by 10 decibels

16.11.2016

Many species of owl are able to hunt in effective silence by suppressing their noise at sound frequencies above 1.6 kilohertz (kHz) - over the range that can be heard by humans.

A team of researchers studying the acoustics of owl flight --including Justin W. Jaworski, assistant professor of mechanical engineering and mechanics at Lehigh's P.C. Rossin College of Engineering and Applied Science-are working to pinpoint the mechanisms that accomplish this virtual silence to improve man-made aerodynamic design - of wind turbines, aircraft, naval ships and, even, automobiles.


This image shows (a,b) Eurasian eagle owl (Bubo bubo) (c) great gray owl (Strix nebulosi) and (d) snowy owl (Bubo scandiacus).

Credit: Ian A.Clark, Conor A. Daly, William Devenport, W .Nathan Alexander, Nigel Peake, Justin W. Jaworski, Stewart Glegg

Now, the team has succeeded - through physical experiments and theoretical modeling - in using the downy canopy of owl feathers as a model to inspire the design of a 3-D printed, wing attachment that reduces wind turbine noise by a remarkable 10 decibels - without impacting aerodynamics. They have further investigated how such a design can reduce roughness and trailing-edge noise.

In particular, trailing-edge noise is prevalent in low-speed applications and sets their minimum noise level. The ability to reduce wing noise has implications beyond wind turbines, as it can be applied to other aerodynamic situations such as the noise created by air seeping through automobile door and window spaces.

Their findings will be published in two forthcoming papers - one called "Bio-inspired trailing edge noise control" in the American Institute of Aeronautics and Astronautics Journal and the other called "Bio-inspired canopies for the reduction of roughness noise" in the Journal of Sound and Vibration.

The researchers - from Lehigh, Virginia Tech, Florida Atlantic University and University of Cambridge - specifically looked at the velvety down that makes up the upper wing surface of many large owls - a unique physical attribute, even among birds, that contributes to owls' noiseless flight. As seen under a microscope, the down consists of hairs that form a structure similar to that of a forest. The hairs initially rise almost perpendicular to the feather surface but then bend over in the flow direction to form a canopy with interlocking barbs at the their tops - cross-fibers.

Among their experiments: suspending mesh fabrics (their original design used wedding veil material!) designed to mimic the effect of the canopy over sandpaper--to create the "roughness"--and simulated air flows using the Virginia Tech Wall-Jet Wind Tunnel.

After realizing that the use of a unidirectional canopy - with the cross-fibers removed - was the most effective - as it didn't produce high-frequency self-noise of the fabric canopies, but still suppressed the noise-producing surface pressure - they created a 3-D-printed, plastic attachment consisting of small "finlets" that can be attached to an airfoil (or, wing). The finlet invention may be retrofitted to an existing wing design and used in conjunction with other noise-reduction strategies to achieve even greater noise suppression.

"The most effective of our designs mimics the downy fibers of an owl's wing, but with the cross-fibers removed," says 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."

###

The research is funded in part by the U.S. Office of Naval Research.

Media Contact

Lori Friedman
lof214@lehigh.edu
610-758-3224

 @lehighu

http://www.lehigh.edu 

Lori Friedman | EurekAlert!

Further reports about: Aeronautics aerodynamic canopies canopy noise level wind turbine

More articles from Physics and Astronomy:

nachricht Smallest transistor worldwide switches current with a single atom in solid electrolyte
17.08.2018 | Karlsruher Institut für Technologie (KIT)

nachricht Protecting the power grid: Advanced plasma switch for more efficient transmission
17.08.2018 | DOE/Princeton Plasma Physics Laboratory

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>