## Aero Function of the Floor

Here are our CFD links and discussions about aerodynamics, suspension, driver safety and tyres. Please stick to F1 on this forum.
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1) If we assume that all the additional winglets and curved slots on the latest front wings are for vortex formation, I would say F1 is still test the quantity limit of vortices.

2) Wanting to stay focused on the leading edge of the floor:

A) Is there any reason to expect that all the new wing vortices are making it to the center and down to the leading edge of the floor? I would think you need to insure that any vortex approaching the floor needs to make its way under and not on top of the splitter. Is this a correct thought?

B) Is there anything about the leading edge of the floor that would cause vortex generation under the floor? That is not normally a property of a straight wing leading edge perpendicular to the flow axis is it?

Shelly, thanks for having me revisit the delta wing properties.

Brian
hardingfv32
13

Joined: 3 Apr 2011

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1)It is not all about vortex formation. To be more precise, sometimes you try to exploit vortices that are already generated because of the wings or because of the bargeboards.
Typical example are the semiciricular channels at the footplate of the front wing endplates: they are ther to house and guide a vortex the tip vortex of the wing.

2) not all the vortices form the front wing make theiru way to the floor. The t-tray produces vortices, the brageborad produces vortices, and those are fed under the floor.
The ttray is a rectangular shaped almost flat plate with higher pressure on top and low on the bottom: tip vortices develop on its two side and go under the floor running along the side of the inner step of the floor
The bargebord has to be seen like a delta wing rotated 90° that relases two vortices, one of which goes under the floor.

The sucion peak at the leading edge of the floor is due to acceleration of the flow around the round edge, like in an airfoil.
When bargebard and ttray vortices flow in this already low pressure region, thy get squeezed and their downforce contribution is enhanced.

Seeing this effect, one could get tempted of squeezing these vortices more... and so ends up putting exhausts there maybe.
shelly
74

Joined: 5 May 2009

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1) What is the purpose of the new semicircular channels now being added away from the endplates? How would the vortex from these channels defer from the vortices coming off the winglets?

2) 'The suction peak at the leading edge of the floor is due to acceleration of the flow around the round edge, like in an airfoil.' So no vortex activity along the leading edge to speak of. The limit of ground clearance at the leading edge maybe becomes an issue of boundary layer thickness? I am envision a graph that plots the gap at the leading edge vs downforce, but I can not determine the properties of system or test. What determines the ideal gap below the leading edge of the splitter/floor in other words?

Brian
hardingfv32
13

Joined: 3 Apr 2011

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1( I explained before /the curved shape at the center is for capturing the floor form the transition between the central anfd the lateral section

2( In my picutre you can see the scution peak from the leading edge *blue vertical line( that crosse the blue vortex strake. I will make another picture to explain myself better
shelly
74

Joined: 5 May 2009

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Some confusion.....

1) I am focusing on the purpose of the new semicircular channels now being added (last couple races) away from the endplates? How would the vortex from these channels defer from the vortices coming off the winglets?

If your answer is referring to this question, then I would appreciate if you give it another try as I missed the point.

2) A new picture is not required for me. I appreciate the strake function.

I am interested in what effects the suction peak at the leading edge of just the splitter. What happens when you vary the ground clearance under the leading edge of the splitter, up or down?

Brian
hardingfv32
13

Joined: 3 Apr 2011

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hardingfv32 wrote:Some confusion.....

I am interested in what effects the suction peak at the leading edge of just the splitter. What happens when you vary the ground clearance under the leading edge of the splitter, up or down?

Brian

Nothing strange happens i suppose. Just another inverted wing in ground effect - so you gain downforce with gap decrease up to some point near the ground, when you suddenly lost all of downforce. Not big deal at the splitter itself, but knowing that the strenght of splitter-generated vorticies depens directly on amount of lift/downforce produced, it will hurt the amount of vortex-downforce under the floor. As this effect is positively coupled with car speed (less downforce = less drag = more speed) you cannot recover without going off the throttle, so it's better to not experience splitter-ground contact in high speed corners .
marekk
2

Joined: 11 Feb 2011

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marekk wrote: but knowing that the strenght of splitter-generated vorticies depens directly on amount of lift/downforce produced, it will hurt the amount of vortex-downforce under the floor.

Are these splitter generated vortices located on the ends (corners) of the splitter? Not generated along the whole width of the leading edge.

Brian
hardingfv32
13

Joined: 3 Apr 2011

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Shelly, i am not sure i understand. If you squeeze a vortex like that and strenghten it, you enhance its low pressure, but this would then act on a smaller (narrower) section of the floor, wouldn't it?
Is there still a net gain in P*A?
Wind turbines are cool, elegant and magnificent. TANSTAAFL!
hollus
45

Joined: 29 Mar 2009
Location: Copenhagen, Denmark

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Before looking into all the complexities of turbulent flow and vortexes it may be helpful to check out Couette Flow and Poiseuille Flow between two parallel plates.

I don't know how to post equations in here so I'll link you to the current equation I have, which makes many simplifying assumptions. I don't have time this moment but later I'll update the link to show the proof, and hopefully find verified experimental data to compare this to.

Couette-Poiseuille Combination

Hope this helps. If you have any questions feel free to ask.
Keith Young
http://racingtech.wordpress.com
keith dot a dot young at comcast dot net
geocities.com/rough_wood (now closed)
rough_wood
2

Joined: 2 Jul 2003
Location: Engineering School

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@hollus: I think that an accelerated vortex gives more downfoce for 3 reasons:
-it is narrower but it's longer (for continuity the volume is the same, so the projected area is equal or bigger)
-for helmholtz it rotates more quickly, so the inside pressure is lower
-being the inside pressure lower, even if the gradient is aggressive, the area around the vortex where the pressure is low will be slightly bigger.
shelly
74

Joined: 5 May 2009

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Harding, I updated the link. It now has a proof and shows how to use the equation. In the new future I plan on making a Matlab code to give flow visualization.

Hope this helps.
Keith Young
http://racingtech.wordpress.com
keith dot a dot young at comcast dot net
geocities.com/rough_wood (now closed)
rough_wood
2

Joined: 2 Jul 2003
Location: Engineering School

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