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Old 06-12-2013, 12:08 PM   #1 (permalink)
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Vortex strake device; reducing aerodynamic drag

I first posted this in the Unicorn Corral because I thought that was were debatable topics were supposed to go. Turns out I was wrong about that somehow, so to gain a wider audience and hopefully discover with other's help the proof that these work as patented, I now re-post it here.

Vortex strake device and method for reducing the aerodynamic drag of ground vehicles Patent Number US7255387 B2
Patent US7255387 - Vortex strake device and method for reducing the aerodynamic drag of ground ... - Google Patents



If I were to think of this as a rain diverter on a roof, such as found over an entry-way I'd say yes, it works.

However we are talking air pressures and vortexes which have a life far from and beyond the moving body.

What say yee?

I found this quote in the forum.

http://ecomodder.com/forum/showthrea...html#post10971
Quote:
Originally Posted by Gone4 View Post
It's possible to used vanned diffusers to reorganize the flow without introducing turbulence.................
Fences and strakes are used on aircraft, so there might be something to this patent in my opinion.

We also see similar (but not exactly the same) features on more and more racing cars, and they are being regulated by the rules because they work, right?

Question:
1. What tests have these devices passed?

2. Where are they being used?

I await your research, and I'll do a little as well when I can get to it.

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Old 06-12-2013, 01:50 PM   #2 (permalink)
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This seems simple enough to test, although I do not believe that my Forester is sufficiently boxy!
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Old 06-12-2013, 02:02 PM   #3 (permalink)
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These vortex strakes have been verified in a full scale wind tunnel.

here is a link to the company that is commercializing them Solus - Vortex Strakes
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Old 06-12-2013, 02:18 PM   #4 (permalink)
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Im sure this legitimate but there is some info missing for those curious about it. These are wind speed specific devices there must be applied air pressure for correct operation. Alot of things that work on airplanes dont do so well at less than 100 mph so remember this when testing. for low speeds it may require 50% more pitch, or surface area etc. etc.

I cant remember which plane but they basically disturbed the air around the whole fuselage so the craft could use a shorter runway. sorta like an extra air cushion under that absorbs major leading edge pressure loads.

Last edited by justme1969; 06-12-2013 at 03:26 PM..
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Old 06-12-2013, 02:32 PM   #5 (permalink)
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Seeing that it targets semis I would assume the speed range they target is 35 mph to 70 mph. Of course I'm sure the speed they optimize the most for would be 65mph because that would be the speed most long haul trucks travel most of their miles at.
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Old 06-12-2013, 02:42 PM   #6 (permalink)
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Quote:
Originally Posted by ConnClark View Post
These vortex strakes have been verified in a full scale wind tunnel.

here is a link to the company that is commercializing them Solus - Vortex Strakes
Solus - Vortex Strakes




Yes, I think this is it because another Patent of Richard M. Wood is being presented by Solus (see below). I'm a little frustrated by the lack of detail on the above. However more detail is in the larger PDF: http://www.solusinc.com/pdf/2003-01-3377.pdf

Solus - Cross-Flow Vortex Traps


Patent US6986544 - Cross flow vortex trap device and method for reducing the aerodynamic drag ... - Google Patents


Both inventions are depicted in the small PDF/Flyer:
http://www.solusinc.com/pdf/flyer.pdf
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Old 06-12-2013, 03:13 PM   #7 (permalink)
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Quote:
Fuel savings of between 2 to 3 percent were demonstrated in the wind tunnel and road tests of this technology.
Quote:
All SOLUS fuel Savings devices have undergone extensive evaluation on the Solus/ODU Representative Heavy Truck (SO RHT) wind tunnel model in the Langley Full Scale wind tunnel.
Apparently, the wind tunnel was not long enough for a semi and trailer, so they used a 1/4-scale model.

Couldn't they have used a real semi with a short trailer?

Also, according to http://www.solusinc.com/pdf/2003-01-3377.pdf:
Quote:
The three devices have undergone extensive operational testing where they have amassed over 85,000 miles of use. These technologies have shown a combined fuel savings of 10% at an average speed of 47.5 mph.
So, 2-3% for the strakes and 10% for all of these devices.

Quote:
SAE Type II road tests are scheduled for Sping '06 to further document fuel savings
I did not see any updates.

From the .pdf:
Quote:
Dates of Operational Testing - July 2001 to March 2002
and July 2002 and March 2003,
Total Trips 232
Total Miles 253600
Baseline Trailer Trips 135
Baseline Trailer Miles 143207
Experimental Trailer Trips 97
Experimental Trailer Miles 110393
Available Trips 155
Available Miles 182494
Baseline Trailer Trips 86
Baseline Trailer Miles 97165
Baseline Trailer Avg. Speed 47.8
Experimental Trailer Trips 69
Experimental Trailer Miles 85329
Experimental Trailer Avg. Speed 47.4

The average speed of each data set was approximately
47.5 miles per hour.
Looks like they did A-B-A-B and the 85,000 miles was from the second "B."

Quote:
Device Improvement in Fuel Economy (%)
CVTD 3.5 to 8.3
UFD 0.8 to 3.3
VSD 2.2 to 4.9
TOTAL 6.5 to 16.5
They also sell side skirts and smooth wheel covers.

cross flow vortex trap gap treatment device (front of trailer)


vortex strake device


undercarriage flow treatment device

Back to my studies!
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Old 06-12-2013, 03:20 PM   #8 (permalink)
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Quote:
Originally Posted by Xist View Post
Apparently, the wind tunnel was not long enough for a semi and trailer, so they used a 1/4-scale model.
Couldn't they have used a real semi with a short trailer?
No.
Length is an important factor, so changing it would require corrections - and those would first need to be calculated as well.
The corrections required when using models in windtunnels are well known, OTOH.
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Old 06-12-2013, 04:14 PM   #9 (permalink)
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Vortex strakes

Quote:
Originally Posted by kach22i View Post
I first posted this in the Unicorn Corral because I thought that was were debatable topics were supposed to go. Turns out I was wrong about that somehow, so to gain a wider audience and hopefully discover with other's help the proof that these work as patented, I now re-post it here.

Vortex strake device and method for reducing the aerodynamic drag of ground vehicles Patent Number US7255387 B2
Patent US7255387 - Vortex strake device and method for reducing the aerodynamic drag of ground ... - Google Patents



If I were to think of this as a rain diverter on a roof, such as found over an entry-way I'd say yes, it works.

However we are talking air pressures and vortexes which have a life far from and beyond the moving body.

What say yee?

I found this quote in the forum.

http://ecomodder.com/forum/showthrea...html#post10971


Fences and strakes are used on aircraft, so there might be something to this patent in my opinion.

We also see similar (but not exactly the same) features on more and more racing cars, and they are being regulated by the rules because they work, right?

Question:
1. What tests have these devices passed?

2. Where are they being used?

I await your research, and I'll do a little as well when I can get to it.
I'd be inclined to look into Hucho's most current edition (which I do not possess).
In his first English translation,back in his section on commercial vehicles,he gets into some of these type of devices.He seems to dismiss them, as their origins are in aerospace applications which in ground proximity fail to provide results as in free flight.
Vortex generators were designed to allow flow reattachment at steep angles,onto a trailing structure.
Truck vans have nothing behind them to reattach to.
And base pressure on the back of the van is a function of the pressure at the separation point.Perhaps the induced vorticity channels a bit of extra kinetic energy into the wake from a very thick boundary layer present at the back of the van.
It's a good question.
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Last edited by aerohead; 06-12-2013 at 04:14 PM.. Reason: spelling
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Old 06-12-2013, 04:26 PM   #10 (permalink)
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Quote:
What say yee?
You'll know they work when you see a second and third example out on the Interstate.


This is interesting because it does the opposite of the Difflow difusser, collecting rather than dissipating the turbulence behind the rear wheels.

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