Why the cut outs in rear wing endplates?

[godlameroso]

For the cut outs, mind you the air on the outside of the end plates have a higher than ambient pressure as they curve slightly outward. The cut outs which are placed at the end of the rear flap reduce the pressure of the air stream and this lowering of pressure follows the low pressure caused by the underside of the wing. As for the slots, simple story it's more of a compromise to achieve more efficiency from the rear wing as it pertains to lift to drag ratio. The slots bleed pressure at the edges where the wing meets the endplates. It allows the airflow to the rear wing to also be more uniform across the wingspan. You lose a little downforce but it's less draggy and more consistent.

[hardingfv32]

Here is a paper on an inverted wing with endplates. It states that the endplate on a wing yields
the formation of two co-rotating vortices originating from the top and the bottom of the endplate. How does this integrate with your slot theories?

A Study of an Inverted Wing with Endplates in Ground Effect

V. Galoul and T.J. Barber

http://espace.library.uq.edu.au/eserv/U ... _16_07.pdf

Brian

[wesley123]

Imo it barely applies here, what I understood is that it is a wing close to the ground, not quite similair to the rear wing.

What causes these counterotating vortices is very simple, the pressure. Underside has low pressure the topside has high pressure, these mix with ambient pressure causing 2 vortices counterrotating from each other.

[marekk]

Imo it barely applies here, what I understood is that it is a wing close to the ground, not quite similair to the rear wing.

What causes these counterotating vortices is very simple, the pressure. Underside has low pressure the topside has high pressure, these mix with ambient pressure causing 2 vortices counterrotating from each other.

Don't think ground effect does change direction of vortex rotation.

Form behind the wing: over the wing flow goes up and to the left (counterclockwise), under the wing flow enters from the left side and goes up (counterclockwise as well).
Both vortexes co-rotate IMO.

[MIKEY_!]

Good stuff guys hope this is helping you lot as much as it is me

[hardingfv32]

The paper said that the ground effect did not effect the vortices at the heights being tested.

Would the air flowing through the slots not have any effect on the vortices being formed? This goes beyond the assumption that they are smaller because of the pressure differential reduction discussed earlier.

Brian

[wesley123]

The paper said that the ground effect did not effect the vortices at the heights being tested.

Would the air flowing through the slots not have any effect on the vortices being formed? This goes beyond the assumption that they are smaller because of the pressure differential reduction discussed earlier.

Brian

The slits in the end plate cause high pressure air to bleed outside of the wing causing it to mix with ambient pressure, overall this reduces vortex strength further down when this air mixes once again with low pressure air.

[MIKEY_!]

Another way to do it might be using hollow endplates, introducing a pipe starting on the inside above the wing and opening under the wing. Reduces pressure diff but also acts as a blown wing. Opinions please...

[hardingfv32]

Anyway these slots could bleed in a non-linear fashion? Say very little flow at low speeds and above average flow at high speeds.

Brian

[godlameroso]

Are you asking if the slots shift the position of the vortices so that their interaction with the wing is speed dependent? Possibly, but also consider this, today's wings have considerable AoA, so even though the cars don't go fast enough to compress the air, the density of the air-stream along the surface of the wings does change, especially with solid end-plates. This is not necessarily a bad thing, it just changes the properties of the air-stream, it adds another variable to consider. In any case it seems there are some clever things that can be done, I wonder how intricate the rear wings will become when teams are forced to focus on it in lieu of restrictions on other parts of the car.

[mep]

Where did you got that picture from?
It can't be taken in Hungary because there where no bwin banners.
Somehow the vortex looks faked for me.

[wesley123]

what makes you think these are faked?

[marekk]

AFAIK it's from winter testing days in Jerez. Found on Gordon McCabe's blog: http://mccabism.blogspot.com/ - lots of good stuff there BTW.

Don't think it's fake, but didn't shot it myself.

[mep]

Ok I think I found the place where you got the picture from:
http://mccabism.blogspot.com/2011/07/mc ... tices.html
So it was some unknown guy who has posted it there. This means we lack a reliable source for the picture.

Well of course it is just a feeling I have and I can easily be mistaken and the picture is real. I just think we should not take it as a given and question the picture itself first before we discuss what we see.
Here some points which make me wonder:
They look different than the vortices we saw in Hungary. The Hungary vortices look very blurry and are hart to detect on a picture, almost invisible. Whereas those on the picture are very strong in colour and sharply defined. They just don't look like the typical condensed air moisture vortices. However when the picture is taken during winter testing (makes sense) than it might be possible that the team used some smoke for the picture. When looking at the rear endplate it seems like there is already some smoke path visible. This can not be from condensed moisture. What I miss then is the smoke trail for the closer endplate.

From my own experiments with smoke I know it is not that easy to capture white smoke with a camera. I was able to do it in a rather dark factory hall. Doing it in bright sunlight is a different story especially when you have the sun in front of you than in the back. Just check the shadow, its rather unlikely to take such a picture.
Again that's what I think. I don't have a problem when the picture is real.

[allstaruk08]

hello people i'v noticed it on other pictures before and just wondered if anyone can explain why the vortices appear to be coming from about half way down (what appears to be the underside of the wing) the inside of the wing then working their way outwards into cleaner air? i thought it was the high pressure part that created the vortices, so is it the high pressure part of the lower element of the wing?

heres a couple of examples of what i mean you can see that the vortices looks like it is spilling out of the cut out into clean air