Anyone use Porous coverings?
I've been reading and found a number of articles on the use of porous materials on the surface of square backed bodies that has a huge reduction in drag ( about 35%) due to the breaking up of the rear air rotation at the back of the vehicle and greatly increasing pressure at the rear. Any one tried this?
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Links?
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This one seemed most applicable
http://www.math.u-bordeaux1.fr/~chab...li/BGM-JFE.pdf
There is also a lot research referring to wing aerodynamics ...especially noise reduction. |
Wow, scanned the link paper and it looks like the computer said it was better. I think you'd find real world testing on big things like cars would yield small results. This seems easy enough to test on a real vehicle, I wonder why it was not done? Computers are susceptible to the dreaded GIGO effect even today in 2015. It has been discussed a lot here on ecomodder mostly regarding golf ball style dimples. It is in fact the very reason I started posting on this forum cause I was thinking of dimpling my GMC pick up.
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http://ecomodder.com/forum/member-fr...dynamics-c.jpg Quote:
With misinformation and factually incorrect statements swirling, Richard Wood is out to ease the turbulence |
This appears to be different than golf ball dimples....
I haven't been able to find much on what materials have been used. A paper on aircraft wings said they used 30% open material for their testing. Standard window screen is about 50%....which is what I'll give a try when I find the time. It appears that the porous material is set above the skin of the object, not directly on it, creating a second air layer that also acted as a jet at the rear edge of the object, which in itself appeared to reduce drag about 13%. I am still digesting this info. Also, in contrast to Mr Wood's diagram the whole top surface and front round edge of the body was covered with the material, not just a small section of the back and the rear. I suspect covering the rear has little or no effect. A recent review (April 2014) of Vehicle drag reducing methods in The International Journal of Mechanical & Mechantronics Engineering ( http://www.ijens.org/Vol_14_I_02/145...JMME-IJENS.pdf) seem to have several methodologies aimed at breaking up the rear vortices in order to increase pressure at the rear surface of the vehicle. Interesting reading.....
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That is interesting. All the best stuff is in PDFs.
I found an infographic that shows 35% for the rear, rather than the 25% total in the one I posted. It's big, so here's the link: 11% to 12% increase in fuel economy for flat backed trucks |
I am seeing more and more aerodynamically modified trailers on the roads already---boattail extensions, wings, even a few aero wheel covers too. If this works as well as they say it does, I suppose I'll be seeing these soon too.
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