Sauber C32 Ferrari

[amouzouris]

This is faaaar more complicated than Bernoulli's principle

[Randomness]

I don't know how to copy that above image. The one posted with the pressure zones, but it is going to help me explain my point

Behind the airbox there is an area of low pressure. When there is low pressure, fluids will automatically move to it as if it is a vacuum. It is the natural order of things.

I am not saying that an obstacle creates better airflow, but examine the behaviour of air bout a winglet. The air is pushed around the obstacle because of the area of high pressure in front of it.

It will then re-join behind it because of the area of low pressure, and the flow will resume at a slightly SLOWER speed because of the drag.

However, an airbox is not a winglet. It swallows a lot of air, which means that the air that goes around it, finds an area of low pressure (like a winglet.) But a smaller volume of air to fill the void. This causes acceleration of the air. Naturally, there will be drag due to the surface of the bodywork, and the air is by no means clean. But a lot of the air that is "pulled in" by the low pressure is clean, and slightly faster than the air around it. It is like creating wind, but on a much smaller scale. Wind is created when there is high and low pressure, and the air escapes the high pressure, into the low pressure areas. This causes acceleration. So, the air in the direct wake of the airbox where the flow re-joins, is accelerated. Because the air is moving from the normal atmospheric pressure, to the area of low pressure behind the airbox (as the image above demonstrates perfectly. Amazouris. You say the flow is not stronger, but that image is actually showing an area of low pressure. Not the speed of the fluid.

I interpreted your post and the use of the word 'stronger' as the wing directly behind the airbox will produce more downforce, which is clearly not the case as can be seen from the pic I posted above, look at the middle of the wing.

Allow me to say that you are wrong..the air behind the airbox is certainly not going to be accelerated. Below you can see a velocity cut plot:
http://farm9.staticflickr.com/8229/8503 ... 07c9_b.jpg

Anw..the conversation has gone wildly off topic...

P.S. Please write my name correctly

Here, Actually, is an image and I will concede that this does half blow my theory out of the water. But are we not witnessing aero-seperation above? I highly doubt that F1 airboxes cause aero-seperation because of the sheer amount of drag. I'd have thought that the air-flow would have re-joined in a far cleaner manner, which is what my premise was based on. But as I don't have an image quite as convincing as yours, I'd concede with this.

[ringo]

Bernoulli's principle can also be derived directly from Newton's 2nd law. If a small volume of fluid is flowing horizontally from a region of high pressure to a region of low pressure, then there is more pressure behind than in front. This gives a net force on the volume, accelerating it along the streamline.

If you derive bernouli from the raw basics, the differential equations, it wont be as simple as we know it.
A lot of "zeroing" out occurs because of negations with potential energy and other things.

[Forza]

I would not take the results as definitive considering the limitations (development tools) and they are more suited to aerodynamics section of a forum as a study of different concepts. I agree with Ringo above as strong interactions between laminar to turbulent air transitions, laminar& turbulent separations and boundary layers and wakes of multiple aerodynamic structures of a racecar can influence the final result. Here one example of 2011 rear wing design (tools used CATIA V5, ModeFrontier, StarCCM+, mesh complexity & model size were both reduced up to 30 times the original cfd model of the full car). Ignore the additional phenomena as at the 2nd image the car is in yaw. But I see what you want to discuss about the slight pressure drop in the central part and the influence of it on the performance of a rear wing.

[Artur Craft]

Directly behind the airbox there is low pressure which is why the air flowing around it gets pulled in, and as a result more air flow reaches the centre of the wing than the outside. You need look no further than an airfoil to understand this..

We are not talking about the DRD wing here, we are talking about the curved wing vs the flat wing. The reason for my post is that whoever it was claimed that the wing produced less downforce for the same drag. But this is simply not true. That was the point. The curved wing collects more air in the centre of the wing. Because this is where the air flow is stronger. On that CFD simulation, lacking an airbox, the air reaching the wing is linear. Which means that it renders the test pretty much useless, as the wing will never be subject to airflow that is not interrupted by the airbox.

Based on everything I know about fluid dynamics, I would say what happens is exactly the opposite.

The monkey seat, for instance, was always explained to be there because of the central section receiving less airflow due to roll hoop blocking it, so the little wing(the monkey seat) is there to help create some downforce in the central section.

About the 2007-2008 rear wings that were mentioned here, those wings are more "cutted" at the sides than "enlongated" at the central. That's why they gave less drag, in that case, it gave less frontal area and also effective chord.

Sauber's new wing is not having less frontal area and effective chord than it's previous wing, it actually have more(that my visual impression, anyway). But despite having more area to produce downforce, it will provide less for the same amount of drag, and that's what the CFD test indicated.

Of course, the whole bodywork of the car, ahead of the RW, will affect how it works, but that's not the point here. Both wings will likely be affected in roughly same manner.

I would be very surprised if, once tested with a whole car on CFD, the new wing would come out with a better L/D than the old one.

The reason for it is simple, that amount of air that reachs the RW is due to the bodywork ahead and not the shape of the wings's, themselves. If there will be less air in central section for one wing, the same will happen for the other and don't expect miracles with the change of air's mass through there.

In this case, a "miracle" would be the "spoon wing" being more effective once tested with the whole car. If you would have half(just an example to make a point) "air mass" reaching the rear wings, with whole car tested, both wings would have half air density reaching, which would imply in half the downforce.

The coefficient of lift/drag of the wings are likely to remain quite the same, in a full car test, that's my point. So, relatively speaking, in a whole car test, the old wing should(at least I guess) remain more efficient

As a note, I think everybody here know that downforce/drag is a function of: air density, area of pressure, coefficient of lift/drag, and speed(squared).

About Williams' wing used in Canada 2011, that is very different to this one. That one was cutted at the center to let the air flow more freely through there, which will result is less downforce/drag.

[Artur Craft]

Behind the airbox there is an area of low pressure. When there is low pressure, fluids will automatically move to it as if it is a vacuum. It is the natural order of things.

This bit is correct.

Air will be pushed to the lower pressure zone but it will take time before it equals ambient atmospheric pressure, so when the air reaches a part near the low pressure zone, it will still have less density of air there, because it will not be equalized with normal ambient pressure, yet.

The rear wing central section, FOR SURE, receives less mass of air than the sides, this is not a guess I'm making here.

Picking on the CFD image that you quoted, the side parts of the wing have darker bits of red because the pressure is greater there, which means more air is going through there.

I would not take the results as definitive considering the limitations (development tools) and they are more suited to aerodynamics section of a forum as a study of different concepts. I agree with Ringo above as strong interactions between laminar to turbulent air transitions, laminar& turbulent separations and boundary layers and wakes of multiple aerodynamic structures of a racecar can influence the final result.

Yeah, with this I also agree.

That CFD test was an indication, a good one I would say. It can't be taken fully but it does indicate that the old wing provides better performance under "normal conditions".

If a race car faces different conditions : "strong interactions between laminar to turbulent air transitions, laminar& turbulent separations and boundary layers and wakes of multiple aerodynamic structures" while on race track with it's entire bodywork, then, the results will be different albeit, again, I don't expect miracles, just some different results

[bhall]

(We love pictures.)

Because teams tend to race cars attached to their rear wings, I humbly suggest that images of components operating in isolation of cars be taken with a whole lot of...



I think this is a lower-drag wing.



I think it's a lower-drag wing, because we know these were lower-drag wings.



Teams only stopped running those wings after the new aero formula put a premium on downforce. So, has something changed in Hinwil that suddenly made downforce superfluous? Or are we asking the wrong question?

We've known for a while now that "the device" has the potential to either "stall" the rear wing with an injection of air perpendicular to the underside of the wing that disrupts the boundary layer and reduces downforce...

...or, conversely, to enhance downforce with an injection of air that energizes the same boundary layer, just like a slotted wing.


(via Scarbs)

So, does it make sense for a team to switch to a lower-drag wing (which inherently means lower downforce) and to further reduce drag (and downforce) with "the device"? Or does it make more sense for a team to switch to a lower-drag wing (which, again, inherently means lower downforce) and to enhance downforce with "the device" to make up the difference?

I submit the latter as the more likely scenario.

[Artur Craft]

I think this is a lower-drag wing.

http://i.imgur.com/eitCJE5.jpg

I think it's a lower-drag wing, because we know these were lower-drag wings.

http://i.imgur.com/owwS9ZT.jpg

Teams only stopped running those wings after the new aero formula put a premium on downforce. So, has something changed in Hinwil that suddenly made downforce superfluous? Or are we asking the wrong question?

I already answered to those in my previous post when mentioned the 2007-2008 cars

Those wings are lower drag because they are sort of cutted on flanks. I will need to seek for 2 pics of the Saubers wings to compare, but I think(right now) that instead of having the sides "cutted", the new RW have the central enlongated.

The same as comparing with Williams's RW used in Canada 2011, ie, not the same thing.

Also, teams used the those low drag RW, pre 2009, because they already had more than enough downforce, at the rear, to balance the df at the front. The same might explain why lot of cars had very low noses before the regulations being changed.

[bhall]

I think it's pretty clear.

[Artur Craft]

Yeah, thanks a lot for posting this pic(it was already posted here but I forgot about it)

It seems "cutted" at the flanks too(as the 2007-2008 ones), which indeed would imply in lower drag

In the CFD test it showed more drag because the modeled wings had same area, effective chord, on flanks as on the "spoon" wing, which would result in more drag as I would expect, and it did. What surprised me was that it doesn't generate much downforce with such shape.

But, obviously, if another test was done with a model "cutted at the sides", rather than enlongated at the center, we would definitely see less absolute drag, albeit the L/D of the "normal" wing would likely remain higher.

This new wing will probably be a spec wing for places like Sepang, China(where there are some long straights), but I won't be surprised if they opted for the "old" one in Melbourne

[steve12345]

velocity/pressures aside - how does the bent wing compare if the central flow vector is angled down a bit? due to some preceeding coanda effect or something.
It would be interesting to see, can models be run with the wing at different angles to the wind source. There may be an optimal angle where the centre works awesome but the outside's rubbish.

It might be useless though. the front and rear of the wings are unlikely to be getting air from the exact same direction, let alone the centre and outside.
Can these cfd models use larger particles as well as course model meshes to speed computations/just to get a vague idea?

[Artur Craft]

velocity/pressures aside - how does the bent wing compare if the central flow vector is angled down a bit? due to some preceeding coanda effect or something.
It would be interesting to see, can models be run with the wing at different angles to the wind source. There may be an optimal angle where the centre works awesome but the outside's rubbish.

It might be useless though. the front and rear of the wings are unlikely to be getting air from the exact same direction, let alone the centre and outside.
Can these cfd models use larger particles as well as course model meshes to speed computations/just to get a vague idea?

I think the CFD programs allow for an angled flow, but I'm not sure.

Nice thing that you brought there. Eventhough I don't think the roll hoop(and etc) would cause much downwash, the flow reaching the RW might have some angle in it and with this relative angle of attack between the wing and the flow, I also guess we could see some quite different results, especially concerning conditions in which the wing will start to stall or how much more the flow keeps laminar or not

[ForMuLaOne]

I wanted to mention or ask something. To me it is impossible that air gets "pushed" into any area. In fact, you do not have any "flow" itself. The car is moving through unmoving airmass ( if you do not care about any wind, which is really the case when you think of a model) but teams simulate an unmoving car which is effected by moving airmass. This is why they also need to corellate their data. So to me it is more like high pressure zones depressurize behind the wing and low pressure zones repressure behind the wing. By creating pressure deltas, any wing or body moving through airmass first creates the delta in pressure, just to take the forces which occure in order to bring the overall pressure to zero again. This is the drag-downforce coefficient. So either we hav a low drag wing which means low pressure deltas between bottom and top of the profile, or a high drag wing, creating higher pressure deltas, thus mediating between those zones by taking the forces and producing downforce. This all works because of inertia of air molecules. But that does not mean, as mentioned above, that moving airparts try to maintain their direction and speed, they just want to maintain in an unmoved state, the "flow" is only the will of a molecule to go back to where it came from. The Sauber wing helps to catch air on it`s way back to the postion it had before the car moved trough it. So they can of course create the same amount of downforce, but the pressure points are further back on the wing profile as it is really curved. They want to move the point of lowest pressure as far to back of the profile as possible, in order to help the diffusor. If this low pressure area helps sucking out the diffusors air, the effect becomes stronger as we all know. Can someone please reply to that thought? Thanks in advance.

[Blackout]

Question; how big are 2013 fuel tanks; how many liters they carry ?



2009 sidepods

[turbof1]

I find it interesting that they use a part of off-season testing to try out the lower downforce/lower drag rear wing. Normally these wings are preserved for just a very few races on the calendar; only Canada and Italy come to mind. Furthermore, they also could test that out at a seperate straightline aero test.

I find it very strange to be honest. It almost looks like they are trying it out to see if it brings advantages to higher downforce tracks too. Infact the whole car seems out of order, having a lower then average nose. It surely can't be that they found so much extra rear downforce; can it?