Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 07-04-2015, 07:12 PM   #1 (permalink)
Master EcoModder
 
Ecky's Avatar
 
Join Date: Dec 2011
Location: New Zealand
Posts: 4,689

ND Miata - '15 Mazda MX-5 Special Package
90 day: 36.7 mpg (US)
Thanks: 2,559
Thanked 2,274 Times in 1,409 Posts
Owl Wings Are Helping Silence Airplanes, Fans, And Wind Turbines

Source

Quote:
Owls are often considered nature’s stealth fighters, and it turns out their ability to silently is a result of a unique wing structure not found in any other bird. Now that researchers know the owl’s secret, they can make lots of stuff silent—everything from bedroom ceiling fans to massive wind turbines.

What contributes to a noisy wing or fan blade as it slices through the air is the turbulence from its trailing edge. But once a team of researchers from the University of Cambridge, Virginia Tech, Lehigh University, and Florida Atlantic University put an owl’s wing under a microscope, they discovered that its flight feathers had a unique soft downy covering, a flexible array of bristles along its leading edge, and a porous fringe coming off the trailing edge.

Working together, these three unique characteristics smooth out the air as it passes over an owl’s wing while also scattering the sounds produced—like how a stealth fighter scatters radar signals—so that it can catch its prey unawares.

To replicate this structure on a wind turbine, for starters, the researchers first experimented with covering those massive blades with a fine mesh material that was similar to what’s used in wedding veils. It succeeded in reducing the blade’s surface noise by a whopping 30 decibels, but ultimately proved impractical for real-world use.

As an alternative, the researchers created a custom prototype material using 3D printing techniques that reduce noise in wind tunnel tests by as much as 10 decibels, without sacrificing aerodynamics. And as this technique is further tested and refined, it will make those giant blades even quieter.

But in addition to reducing the amount of noise pollution generated by a massive wind farm, the new coating could allow wind turbines to actually run at higher speeds, making them more efficient and increasing their power output. And while applying the material to a plane’s wings is a little more challenging given the speeds they travel at, it has the potential to make an air craft more fuel efficient and also more comfortable and quieter for those riding inside.

What I wonder is if adding a fine mesh coating that reduces trailing-edge drag would add enough skin friction to offset the reduction in turbulence. Either way though, silence is something to be valued.

  Reply With Quote
The Following 3 Users Say Thank You to Ecky For This Useful Post:
AbramWagner (07-04-2015), BamZipPow (07-09-2015), user removed (07-05-2015)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 07-04-2015, 09:41 PM   #2 (permalink)
EcoModding Lurker
 
Join Date: Dec 2014
Location: North East Pennsylvania
Posts: 61

Hatch - '86 Honda Civic DX
90 day: 50.81 mpg (US)

Sedan - '92 Honda Civic Lx
Team Honda
90 day: 59.43 mpg (US)
Thanks: 116
Thanked 7 Times in 7 Posts
Interesting how how a lot of designs they look to nature and copy it.
__________________
  Reply With Quote
Old 07-05-2015, 02:44 AM   #3 (permalink)
EcoModding Apprentice
 
Join Date: Apr 2012
Location: Sneek
Posts: 156

Focus - '05 Ford Focus tdci Futura
Thanks: 66
Thanked 34 Times in 24 Posts
Nature has found its ways already via evolution. Almost all we know now comes from nature. But the details from alot of stuff is getting griped bij people now.
__________________

  Reply With Quote
Old 07-05-2015, 01:08 PM   #4 (permalink)
EcoModding Lurker
 
Join Date: Dec 2014
Location: North East Pennsylvania
Posts: 61

Hatch - '86 Honda Civic DX
90 day: 50.81 mpg (US)

Sedan - '92 Honda Civic Lx
Team Honda
90 day: 59.43 mpg (US)
Thanks: 116
Thanked 7 Times in 7 Posts
Quote:
Originally Posted by NickelB NL View Post
Nature has found its ways already via evolution. Almost all we know now comes from nature. But the details from alot of stuff is getting griped bij people now.
I was thinking more along the lines that it points to intelligent design of a creator but every one is entitled to their opinion.
__________________
  Reply With Quote
Old 07-05-2015, 02:32 PM   #5 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 23,370
Thanks: 6,594
Thanked 7,452 Times in 6,076 Posts
Small-'C' creator, I see. I lean more toward the Anthropic Principle, Weak or Strong.

This is a good example of Biomimetics, and a different approach to semi-permeable surfaces generally.

Quote:
...the researchers first experimented with covering those massive blades with a fine mesh material that was similar to what’s used in wedding veils.
The reporter covers the Society page? A furry trip strip on the leading edge and a serrated trailing edge would be more analogous.

Edit: Then there is this from The Register:

Engineers 3D-print ROBOT SEAHORSE, then BATTER it with rubber mallets

It being El Reg, you'll notice the title in the actual URL is "/seahorse_tails_robot_tales_were_all_going_to_die/".

Last edited by freebeard; 07-05-2015 at 03:03 PM..
  Reply With Quote
Old 07-05-2015, 03:17 PM   #6 (permalink)
EcoModding Lurker
 
Join Date: Feb 2012
Location: UK
Posts: 99

Panzerwagon - '02 Skoda Fabia
90 day: 53.88 mpg (US)
Thanks: 1
Thanked 10 Times in 9 Posts
I'm sceptical that there'll be any perceivable decrease in airplace noise (both interior and exterior) but the Wind Turbines is certainly an interesting application and a turbine noise is often used by anti-wind turbine groups.

Quote:
Originally Posted by AbramWagner View Post
Interesting how how a lot of designs they look to nature and copy it.
Similar to how wing tips have been adopted only fairly recently.

It's a funny thing, we've known for years that animals are capable of some amazing things that we would do well to replicate, but the technology and funding to really look into it has only recently become available in some instances.
  Reply With Quote
Old 07-05-2015, 10:52 PM   #7 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 23,370
Thanks: 6,594
Thanked 7,452 Times in 6,076 Posts
Quote:
Originally Posted by RunningStrong
I'm sceptical[sic]...
Latest practice with turbojets is a serrated trailing edge. It must be quantifiable.



The real fun is when you take what Bucky Fuller called 'generalizable principles' from nature and apply them to things nature never addressed. Beetle wings to LCD screens kind of stuff. Or Bucky-tubes/balls and graphene.
  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
NeilBlanchard (07-05-2015)
Old 07-06-2015, 05:13 PM   #8 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 14,509
Thanks: 22,513
Thanked 6,711 Times in 4,251 Posts
trailing edge

Automotive drag is associated with separation-induced pressure drag.
If you have a streamlined shape,the trailing edges will also be streamlined and the car will only suffer from surface friction drag which cannot be removed.
Any 'feather down' attached to the aft-body would already be embedded within the thickened turbulent boundary layer and only add turbulence and drag.
As to noise,most of that is coming from the tires.
Owls fly at very low flight velocity,below critical Reynolds number.They're in a laminar boundary layer up to maximum cross-section and 1st minimum pressure on the wings.It's nothing like an automobile.
Their down is attached to nerve endings.As their angle of attack approaches stall,their central nervous system will cause the bird to morph it's wings such to defeat the stall,within a closed-loop feedback system.Again,it's nothing like an automobile.
Owl technology was very important during the Vietnam War,where the USA had aircraft operating overhead at very low altitude which could not be heard from the ground.A large suite of features combined to allow the acoustic stealth performance.NASA has studied Raptor/Owl acoustics extensively.
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
The Following 4 Users Say Thank You to aerohead For This Useful Post:
BamZipPow (07-09-2015), Ecky (07-06-2015), Piotrsko (07-07-2015), Xist (07-06-2015)
Old 07-07-2015, 01:36 PM   #9 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 23,370
Thanks: 6,594
Thanked 7,452 Times in 6,076 Posts
Quote:
A large suite of features combined to allow the acoustic stealth performance.NASA has studied Raptor/Owl acoustics extensively.
IIRC it was a light plane with a five-bladed prop and a large (like the whole tail of the fuselage) muffler.

Now we have Black Helicopters.
  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
aerohead (07-08-2015)
Old 07-08-2015, 02:14 AM   #10 (permalink)
Master EcoModder
 
Join Date: Mar 2008
Location: USA
Posts: 562
Thanks: 1
Thanked 69 Times in 55 Posts
Google for Lockheed YO-3 aircraft, essentially a Sweitzer sailplane with 5 or 6 bladed slow moving propeller, engine, and a long muffler. It was a dog to fly, being under powered and over weight, but never took a round of enemy fire, since it pretty much flew at night and Charlie never heard it coming. There is an alumni website for YO-3 guys.

The FBI had a couple of these Army surplus planes at Pt. Mugu in the late '70s. Used them in the Patty Hearst kidnapping, etc. I talked to the crew chief, who told me that if one flew over in the dark about 50 feet overhead, all you'd hear was about the same as a flock of birds at that height, like ducks or geese, not honking.

NASA has or had one of the final versions, 3 paddle blade wood prop, to carry microphones to test helicopter noise, flown in close formation. Based at an old (Moffat?) Navy airfield at the south end of the San Francisco Bay.

  Reply With Quote
The Following 2 Users Say Thank You to Otto For This Useful Post:
aerohead (07-08-2015), Xist (07-08-2015)
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com