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Old 03-24-2015, 08:35 PM   #48 (permalink)
chillsworld
I got ideas
 
Join Date: Aug 2014
Location: Georgia, United States
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Quote:
Originally Posted by aerohead View Post
These vehicles are dominated by surface friction drag.
Automobiles operate in a fully-turbulent boundary layer,their skin friction is already minimized.
The automobiles drag is dominated by pressure drag which is a function of separation.It is the turbulent boundary layer which allows automobiles to achieve as low a drag as they'll attain.
The premise of aerodynamic streamlining is to reduce or eliminate separation.This is a function of shape.
Virtually all attempts to apply non-automotive streamlining tricks to automobiles have failed.They're a completely different animal.
After reading Song et al's paper I have no confidence that they accomplished anything at all.I believe that their work is extremely flawed.
Quote:
Originally Posted by aerohead View Post
Aeronautical engineer,Gary O.Wheeler,inventor of the Wheeler Vortex Generator has been active in automotive drag reduction since the 1990s,offering his VGs for those with notchback cars.There's an article about him in my photo archive.
As long as notchbacks are produced,there will always be an opportunity for drag reduction.Whether or not it makes it into production remains to be seen.
There are manufacturing considerations and aesthetic considerations.The average car buyer might never be ready for VGs.
The trend appears to be,to follow the organic forms of a hundred years ago,which don't produce separation over their body length.
Vortex generators are used on airplanes. They are capable of creating a 50% decrease in drag, as per NASA studies in the 90's. These same vortex generators are used on trucks, cars, etc with success (which varies according to who you ask). You state a plane has surface friction and is streamlined, where as a automobile has turbulent flow creating minimal surface friction on a non-streamlined object. Yet the vortex generator has a (generally) positive impact on drag in both scenarios, depending on placement and size. They accomplish the same goal, lessening separation, under what you describe as dissimilar situations. So I guess I don't understand why something else couldn't work in both scenarios, and I guess this is why I never became and engineer But since the most specific, and data filled study I could find, is apparently flawed... I guess I got no choice but to go along with the flow (get it, it's a pun )

Thanks for taking the time to read the study, and to post accordingly

~C
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I'm really beginning to like eco-humor
Quote:
Originally Posted by aerohead
PS you could add hamsters inside for a 'bio-hybrid' drive.
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