Rear Wing Comparison

[amouzouris]

The user named Artur Craft kindly asked me a few days ago to carry out a CFD test comparing a normal rear wing to the one sauber tested in barcelona where the angle of attach varies along the span of the wing.



So here are the results. (I will not post the Lift and Drag figures as some users might think that they the exact figures of an F1 RW and misinform other people as well, which can come back to bite me...so I will only post L/D ratio)

I have tried to get the wings to produce the same Lift so that I could examine just one variable, drag. I got them to produce about the same lift. The regular RW produced only 1.6% more lift. What is interesting is that it produced 14.7% less drag. The reason for the Sauber-inspired RW being more draggy, I think, is the stronger vortex produced because of the varying lift produced along the span of the wing.

Normal Rear Wing:

L/D Ratio: 2.6









Sauber (inspired) Rear Wing:

L/D Ratio: 2.2

[flynfrog]

Nice work. I would suspect that other features of the car like the airbox might effect the reason for the dished wing.

[amouzouris]

Nice work. I would suspect that other features of the car like the airbox might effect the reason for the dished wing.

Well, the central part sits behind the airbox which would alter the lift and drag produced by the RW. This and about a billion other factors would affect it! But unfortunately I dont have a powerful enough computer to test it properly..

[flynfrog]

Nice work. I would suspect that other features of the car like the airbox might effect the reason for the dished wing.

Well, the central part sits behind the airbox which would alter the lift and drag produced by the RW. This and about a billion other factors would affect it! But unfortunately I dont have a powerful enough computer to test it properly..

I do like your approach of equalizing the lift between the wings to eliminate variables. Not sure what you have for a computer but I wonder if you could get away with a simple tub in front of both maybe do the back half of the air box with a blunt edge in front. Then again even the FW end plates have an effect on the RW of an F1 car. Once again nice work.

[flyboy2160]

nice job a!

couldn't that dished shape be involved with a passive blown/sucking drag reduction system? if you placed a simple slim swan neck under the center of the wing and blew/sucked from it, which wing shape performs better at drag reduction? (scarbs thinks there are holes that blow laterally, but i can't see well enough in the pictures to say so....)

[Blanchimont]

Thumbs up for this simulation!

When i look at the pressure distribution of the upper wing element on both the normal and sauber-inspired rear wing i can see a pattern that repeats every ~100mm and looks "wrong" compared to the other surfaces where there are smooth transitions of the colours. How does the mesh look like in these areas where the patterns emerge?

Edit:
If possible, could you maybe provide a longitudinal cut through both rear wings, so that the wing profiles can be seen? Thanks in advance!

Edit 2:
Could you provide the frontal area of both rear wing versions if it doesn't take to much time? Thanks again.

[Artur Craft]

I'm glad to see that my request was also usefull to other members.

I don't know why this wasn't being discussed more in the forum, I think we all know have to talk/discuss/investigate why are some teams doing this

Red Bull is doing something like this since last year(at least, on later GPs), Sauber is using now. Ferrari uses this convex main plane's underside entrance in the entire span of their wing

If this gives less downforce for the same drag(I know amouzouris approached it in the inverse but it works both ways), why some are teams using a less efficient wing? The benefit is somewhere else and we shall look for it

[hollus]

The alignment is far from perfect, but Sauber's spoon wing does not have an extended center, it has a shallower profile at the end plates. The center is likely using the whole extension of the legality box, like any other team.
The shallower profile at the end plated likely can be compensated by less or smaller louvers.

In the CFD, there is simply more wing in the Sauber. Maybe there are diminishing returns with a larger and larger wing, and you are flirting with separation due to the increased angle of attack? If there is no separation, drag would still be increased by the effectively increased angle in the central section, which is now facing less downwards and more backwards.

[amouzouris]

@flynfrog some rough CFD work I have done earlier this month siggests that the neck below the wings creates some disturbance, also the detached neck blows 90 degrees to the wing, while the neck attached to the wing blows at 90 degrees to the airflow.

@Blanchimont You are right about the repeating pattern, it is probably because of the low computing power (relative to what the teams have) of my computer. I will try to get the cut plot asap. Not sure what you mean by providing the frontal area, actual numbers or pictures?

@hollus You are right about possibly flirting with separation, so i will try and get some number for a lower AoA

[flyboy2160]

a,

are you running a viscous solution?

[amouzouris]

Nope! just air!

[flyboy2160]

Nope! just air!

no, i'm not joking...are you running it as just potential flow or as viscous flow?

[amouzouris]

I am solving (not me solidworks) viscous flow by iteration

[flyboy2160]

I am solving (not me solidworks) viscous flow by iteration

ha! i also have (the expensive) solidworks flow sim package, not cheapo the built-in one. i'm amazed that you didn't see separation off the backs of the wings with a viscous solution. their camber lines are certainly steep enough to separate the flow.....

[amouzouris]

I am solving (not me solidworks) viscous flow by iteration

ha! i also have (the expensive) solidworks flow sim package, not cheapo the built-in one. i'm amazed that you didn't see separation off the backs of the wings with a viscous solution. their camber lines are certainly steep enough to separate the flow.....

I did! but it is not visible in either of the pictures I've posted i know!

EDIT: It is very very expensive yes