Rear Wing Fences

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hardingfv32
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Rear Wing Fences

Postby hardingfv32 » Mon Apr 16, 2012 5:10 pm

Image

Wing Fences...."They obstruct span-wise airflow along the wing, and prevent the entire wing from stalling at once" on aircraft wings.

The under side of the RW main element seems to have a 3D contour.

Would the fences have to fit in a the rear wing spec box?

Brian

shelly
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Re: Rear Wing Fences

Postby shelly » Mon Apr 16, 2012 5:18 pm

Slot gap spacers are prescribed by the rules. I think the cutouts that reduce the chord length are there to make reattachment easier when the drs closes down
twitter: @armchair_aero

hardingfv32
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Re: Rear Wing Fences

Postby hardingfv32 » Mon Apr 16, 2012 5:47 pm

How about the fence on the bottom of the main element?

Brian

shelly
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Re: Rear Wing Fences

Postby shelly » Mon Apr 16, 2012 8:12 pm

As above: it is a spacer prescribed by the rules. The rules say its shape has to be a offset of the aerofoil shape
twitter: @armchair_aero

hardingfv32
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Re: Rear Wing Fences

Postby hardingfv32 » Mon Apr 16, 2012 9:10 pm

So they are claiming that the fences are slot gap spacers that happen to extend to the front of the wing.

Brian

Crucial_Xtreme
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Re: Rear Wing Fences

Postby Crucial_Xtreme » Mon Apr 16, 2012 9:55 pm

I was under the impression the V-Grooves help curb drag (vortices) by pushing airflow across the width of the section, instead of having pinch points. No?

hardingfv32
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Re: Rear Wing Fences

Postby hardingfv32 » Mon Apr 16, 2012 10:55 pm

Pinch points... what evidence do we have that they exist on the RW? I have a CFD sim that does not indicate any pressure buildup at say the end plates junctions.

That is why I wonder what the fences are for. I do not see why the flow should want to move sideways on the wing surface. could there be a concern with yaw conditions?

Brian

bhall
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Re: Rear Wing Fences

Postby bhall » Tue Apr 17, 2012 6:03 am

They probably quicken the process by which air flow is reattached when DRS is disengaged.

aleks_ader
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Re: Rear Wing Fences

Postby aleks_ader » Tue Apr 17, 2012 6:51 pm

Interesting rear wing concept + pernamet f duct = could be win win combination
"And if you no longer go for a gap that exists, you're no longer a racing driver..." Ayrton Senna

marekk
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Re: Rear Wing Fences

Postby marekk » Tue Apr 17, 2012 10:36 pm

hardingfv32 wrote:Pinch points... what evidence do we have that they exist on the RW? I have a CFD sim that does not indicate any pressure buildup at say the end plates junctions.

That is why I wonder what the fences are for. I do not see why the flow should want to move sideways on the wing surface. could there be a concern with yaw conditions?

Brian


I do not see why it shouldn't.
Pressure gradient = moving air. To the endplates on the high pressure side, to the center on the low pressure side.
Wing fences are not that rare, even in aviation, and help a little with wing's efficiency.

hardingfv32
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Re: Rear Wing Fences

Postby hardingfv32 » Wed Apr 18, 2012 2:11 am

Note how the pressure actually looks lower near the end plates. I question the commonly given reason for the endplate louvers.

Brian

Image
By hardingfv32 at 2012-03-26

Lycoming
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Re: Rear Wing Fences

Postby Lycoming » Wed Apr 18, 2012 3:02 am

Not really comparable. The foil in the CFD doesn't have nearly the amount of camber or the same angle of attack.

just curious, what is the "common" explanation fort he louvres?

hardingfv32
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Re: Rear Wing Fences

Postby hardingfv32 » Wed Apr 18, 2012 5:22 am

Lycoming wrote:Not really comparable. The foil in the CFD doesn't have nearly the amount of camber or the same angle of attack.


I bet your next post after I the correct the angle of attach is going to be "but it is not the whole car!"

Well I hate to burst your bubble but this is as good a sim as you are going to find on this area of the car. Please feel free to post a sim that demonstrates the angle of attach matters. I would be thrilled to see it, as it toke a lot of effort to find the one I posted.

Brian

Crucial_Xtreme
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Re: Rear Wing Fences

Postby Crucial_Xtreme » Wed Apr 18, 2012 12:34 pm

hardingfv32 wrote:
Lycoming wrote:Not really comparable. The foil in the CFD doesn't have nearly the amount of camber or the same angle of attack.



Well I hate to burst your bubble but this is as good a sim as you are going to find on this area of the car
. Please feel free to post a sim that demonstrates the angle of attach matters. I would be thrilled to see it, as it toke a lot of effort to find the one I posted.

Brian


Probably true, but Brian that doesn't mean this analysis is representative of modern day(2011-2012) Rear Wings.

Think about why vorticies are present in this area: high pressure above the wing, low pressure beneath it & ambient pressure on the side of the endplate. What happens when these three meet? The high pressure flow naturally moves towards the low pressure area. This sets up a tumbling motion and a vortex is created.

Image

n_anirudh
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Re: Rear Wing Fences

Postby n_anirudh » Wed Apr 18, 2012 12:49 pm

Lycoming wrote:Not really comparable. The foil in the CFD doesn't have nearly the amount of camber or the same angle of attack.

just curious, what is the "common" explanation fort he louvres?


The gills are to bleed out air from the high pressure region above the wing to weaken the tip vortices... their orientation and alignment is critical and teams vary this...




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