Double Floor

[horse]

I saw there was no thread on this concept yet, and I wanted to discuss the aerodynamics of the double floor.

Here is a good picture of the Torro Rosso from the STR06 thread.



and here is Scarbs's blog on the subject: scarbsf1/toro-rosso-str06-double-floor

This part of his explanation interested me:

driving more airflow over the diffuser... creates higher pressure above

What is the mechanism for this? Is it, instead, less low than would be if it goes around the sidepods?

I thought one possibility for generating a higher pressure here is the aerodynamic response of the sidepods themselves. Now they are separated from the floor, they look a lot like aerofoils at a positive angle of attack, so is it reasonable to assume that there is a high pressure area above the floor generated by the side pod itself?

What's really confusing about that, though, is that this means the side-pod is now a lifting body, which is working against the gains made by opening up the floor. What am I missing here?

[Sebp]

The sidepod as I understand it works as an inverted aerofoil. Similar to ground effect way back when. So the air the air is sped up between the two floors to create a low pressure zone there. And this high speed air later is led over the diffuser as you quoted from scarbs.

[horse]

I see what you're saying, but if you generate a low pressure area under the sidepod, then does this not reduce the effectiveness of the floor? It also contradicts Scarbs' "higher pressure".

[Callum]

Check this out: viewtopic.php?f=6&t=5672

[horse]

Thanks for the link Callum. The sidepods of the F92A look very neutral to me, as in they have no aerodynamic influence.

Perhaps TR are trying to achieve the same thing, in that the angle of attack is cancelled by the curved underbelly of the sidepod?

Having aerodynamically "neutral" sidepods must be the only way to go, surely?

[Sebp]

Let's aasume for the sake of argument that the sidepod does change the airspeed between it and the floor. What you get is a low pressure zone, the result of which beeing downforce. Now this quick air is routed over the diffuser. But I guess the air coming out of the diffuser from under the car is quicker making for a second pressure differential. So ideally to maximise this differential you would want to just about stall the air from the sidepods. But a compromise must be achieved because you have take the beam wing into account.
Am I still making sense

[horse]

I kind of get where you are coming from. Let me say it back to you.

Currently the floor makes a "double suction peak" of low pressure at its leading edge and the diffuser. If you could use the sidepod to create another suction peak, somewhere near it's centre line (away from the two peaks of the floor), then you get three low pressure zones over the length of the car where once you had two.

In addition, if you can return flow under the side pod to ambient pressure after it's gone through the foil then it will also improve the operation of the diffuser as per the F92A.

Is that what you were getting at, Sebp?

Still, is that STR06 pod orientated the right way to get this effect? It may well be, you know. Notice the greatest restriction under the sidepod is roughly halfway down the length of the floor.

Wow, that's clever.

[godlameroso]

You could further accelerate the air by using the radiator exhausts, as well as engine exhausts.

[JohnsonsEvilTwin]

Still, is that STR06 pod orientated the right way to get this effect? It may well be, you know. Notice the greatest restriction under the sidepod is roughly halfway down the length of the floor.

Wow, that's clever.

how easy will it be for other teams to mimick this effect now we know the homologation rule has ceased for 2011?
Its being speculated that Mercedes have somthing similar, but they will only test the solution in a couple of weeks.

[marekk]

From this perspective it looks like an regular (but inverted) airfoil with some serious camber and angle of attack, generating some amount of lift facing down.
Working in ground effect due to near floor it should have very low induced drag.
You loose of course some downforce from this part of the floor underneath , but there is very little to loose in this region anyway.
Very important in my view is that this downforce is almost irrelevant to ride hight - it depends only on your speed.

[marekk]

If someone's interested, there is a nice airfoil simulation applet at NASA: http://www.grc.nasa.gov/WWW/K-12/airplane/foil3.html.
Achievable downforce and drag figures are quite surprising.