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Old 04-06-2021, 07:31 AM   #1
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Triangular protrusions

Anyone know what the purpose of these triangular shaped protrusions?
https://sportsmobile.com/van-invento...dy-ford-e-150/
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Old 04-06-2021, 07:37 AM   #2
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Esthetics - I’ve read that some claim it helps control wind noise, but where those are placed it’s not going to make any difference.
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Old 04-06-2021, 07:53 AM   #3
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Vortex generators, or airtabs. Whether effective on a van at road speeds is another question, they have to be properly designed and fitted to have a chance at making a difference, otherwise just aesthetics.

Article discussing on cars:
https://www.motorbiscuit.com/do-vort...elp-road-cars/

Interesting test on a Sprinter with one brand, no real difference:
https://www.buildagreenrv.com/vorbla...ator-mpg-test/

Ecomodder forum discussion:
https://ecomodder.com/forum/showthre...nefits-97.html
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Old 04-06-2021, 08:29 AM   #4
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Interesting thread I started freaking seven years ago !! Related info re noise and crossbars.

https://www.sportsmobileforum.com/fo...cks-12667.html
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Old 04-06-2021, 08:39 AM   #5
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In certain fluid dynamics flow regimes, turning laminar flow into turbulent flow reduces drag......that's what those things are supposed to do...they are vortex generators.........whether they provide any meaningful benefit to gas mileage, etc...who knows.


Please let us know if your van is getting 20mpg . If things like this worked for improving gas mileage the car manufacturers would be all over them to meet the CAFE fuel economy requirements.


This is the same reason that golf balls have dimples..to break the boundary layer air flow around the ball into turbulence. If you take 50 balls that are smooth and 50 balls that are dimpled and drive all of them you will see a statistically significant increase in distance in the dimpled balls...*assuming that you are not a hack golfer.
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Old 04-06-2021, 09:11 AM   #6
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Would those help any with air flow going past a trailer?
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Old 04-06-2021, 04:35 PM   #7
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Thanks for all the info. It does appear that vortex generators may be helpful for high speed vehicles but for standard driving they are probably not giving any benefit at reducing drag significantly.
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Old 04-06-2021, 08:04 PM   #8
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As far as I can tell those things are for people who would rather buy ugly add-ons for their cars than gas.....and they still wind up having to buy as much gas.

I see trucks on the highway almost every day with those silly things wrapped all the way around them.

Nonsense IMO.
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Old 04-06-2021, 09:53 PM   #9
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Quote:
Originally Posted by 86Scotty View Post
I see trucks on the highway almost every day with those silly things wrapped all the way around them.

Nonsense IMO.

The tail flaps on the semi trailers are there to do exactly the opposite of these things....when deployed they are supposed to keep the boundary layer air flow down the sides of the trailer laminar when it reaches the back of the trailer....reducing the "wake" behind the trailer....just like those long tear-dropped shaped helmets the road bike velodrome guys wear.
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Old 04-06-2021, 10:40 PM   #10
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The first time I ever saw vortex generators used on passenger vehicles was with the Mitsubishi Evo. Mitsubishi published this white paper regarding their use on a sedan.

Assuming you don't want to read the whole paper, the main conclusion is:

Quote:
Application of the VGs of the optimum shape determined through the abovementioned analyses to the Mitsubishi LANCER EVOLUTION showed a 0.006 reduction in both the drag coefficient and lift coefficient.
Obviously one can't accurately extrapolate the effect it would have on a box-like vehicle like our vans or a semi trailer, but the effect (however small) is probably measurable. As for whether it's worthwhile...
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