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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 03-25-2015, 06:04 PM   #81 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 12,378
Thanks: 19,922
Thanked 6,203 Times in 3,826 Posts
drag of open-faced v-section

Quote:
Originally Posted by aerohead View Post
The open-faced strut would behave much like angle iron in the airstream.I don't have that with me,but I believe that the Cd is over 1.00.
The jet created would be asymmetrical with respect to the mirrors wake and could possibly make things worse.
The mirror in free flight would be Cd 0.30 - 0.25
*All I could find was a sub-critical Reynolds number Cd for an angle iron section,normal to the flow,with no slant.It is given Cd 2.2 by Hoerner.
*Cd 2.0 if a solid section.
*Turned with pointed part into the wind,Cd 1.45.
*Ditto,with solid section,Cd 1.55.
--------------------------------------------------------------------------
The only structure shown with sub,and supercritcal Reynolds number was for a circular rod section.
* subcritical = Cd 1.2
*supercritical = Cd 0.35 (only 29.1% of the sub-critical Cd)
There's no telling if any of the other structures would behave the same,but for estimation purposes,it may be all we can do.
*As to the slant,you might just do a simple force diagram and use the Pythagoriun theorem to get velocity vector values angled,and use them with the Cd.

__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 03-25-2015, 06:20 PM   #82 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 18,813
Thanks: 5,230
Thanked 6,206 Times in 4,972 Posts
  Reply With Quote
The Following 2 Users Say Thank You to freebeard For This Useful Post:
aerohead (03-25-2015), BamZipPow (03-25-2015)
Old 03-26-2015, 04:17 PM   #83 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 12,378
Thanks: 19,922
Thanked 6,203 Times in 3,826 Posts
'mirror' / mount shapes/drag

here are a few structures which have been wind tunnel tested which might shed some light on mirror bodies









__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Old 03-27-2015, 09:53 AM   #84 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 3,797
Thanks: 46
Thanked 2,521 Times in 1,764 Posts
Quote:
Originally Posted by aerohead View Post
Here is an interesting CFD and wind tunnel study of 'passive jet' mirrors.
Results are a bit quirky,and some off-car testing (which is a no-no) but interesting!http://www6.miami.edu/acfdlab/public...14-01-0584.pdf
These concepts are very similar to the way I think my roof wing with leading air slot works, see (Fig 3).

Very cool.

__________________
George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
  Reply With Quote
The Following User Says Thank You to kach22i For This Useful Post:
aerohead (03-27-2015)
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com