CFD - Computational Fluid Dynamics, Motorsport, Formula 1

[CFDruss]

Hello Everyone,

This Thread is mainly for your aerodynamic learning pleasure!!! Me and a number of other F1Technical members have teamed up to create Geometries and then analyze their aerodynamic characteristics.

Please all feel free to contact me either via email or by posting on the thread if you want your own CAD model run in CFD, or if you have any questions about the models shown.

My Email: CFD@Play101.fsnet.co.uk MSN:Rascal1001@Hotmail.com
Keith Young (CAD Modeler): keith.a.young@comcast.net
Site Owner: tombatore@hotmail.com

In order to try and prevent overloading of the thread with pictures, all the pictures in the thread are being grouped and links will be posted for each model that CFD has been used on, so if pictures you seen at previous visits are not here, try the links The links will be posted below. Please continue to post in this thread with any questions or comment you may have.

Enjoy!!!!



Links

Rear Wing Model 1 (Alero)


USA SCCR Race Car - New

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[KeithYoung]

Russ, i do have files. I emailed you a while ago i figured id let you know on the forum as well. No files atached yet though. keith.a.young@comcast.net is my email, id like to discuss things before file swapping. Regards Keith

http://home.comcast.net/~keith.a.young/Picture1.jpg



here is one of the files. anyway my lunch break is coming to an end, hope to hear from you soon.

[KeithYoung]

Well I found a Ferrari front wing modeled online, it was VERY dirty and not usable. So i took it in and made some changes and cleaned it up, here is a picture of the model.



http://home.comcast.net/~keith.a.young/ferrar1new2.jpg

I sent this wing to Paul and Russ, Russ said he will run it soon and Paul usually tells me after he runs things hehe, so there hopefully will be some nice eye candy within the next few days... I can also take this wing and completely redo it, changine the wing section and even the sweep with a little work, the key was cleaning up the DWG, after that things go like a snap. I used UG NX for the modeling and I just got NX 2 today and thats what the screenshot is of, I must say I like the new changes in NX 2 . Anyway back to working. If anyone else knows aero well or has a CFD program feel free to contribute!! This has been a joy working with Paul and Russ and I'm sure finding more partners wouldnt be a bad thing.

Cheers
Keith

[Goose]

I was wondering if I could get a copy of the drawings?(to use with autocad)
Just to play with.
jgiesbrecht@monarch.net

[NickT]

Wow Russell, absolutely fantastic work. Its great to see what is really going on. I have been looking at one of the other forum topics - William rear wing - that is discussing rear wings. There are two items there that have been discussed.

Serated gurneys (supposed to give similar downforce with less drag over a regular gurney) and end plates with cut outs that follow the upper surface of the wing profile (suppossed to be more stable when the wing is in yaw but with a slight reduction in straight ahead performance, and apparently use in IRL and CART on ovals. scarbs thinks the cutouts are more to do with vortex management than yaw performance).

I don't suppose you could model the effect of these so we could see whats happening? I think the rear wings are two element affairs and not the three element one you have used here, making the endplate cutouts easier to form.

Cheers

Nick

[CFDruss]

Thank you Nick T, Im grateful that you liked the work, sorry the report is a little brief, but like I said, I was in a rush.

If you or anyone has or can do the CAD geometry of the designs you are interested in then I will analysis the best I can..........of an F1 or F3 company can offer me a job!!!!!!!! Yeah, I wish

Cheers

Russ

[scarbs]

More excellent work, I have a 2001 Arrows FWEP if you want to more accurately model this part..!

[scarbs]

Russ,
Excellent work, Its rare for any of us to have access to clear images of aero components at work. If we could just build up a library of this stuff to explain the action of the various (simpler) solutions we’d all get something out of it.

For example (and as Nick asked) putting the notch in the endplate, flush with the flap.

Having seen in your example the strong vortices trailing the wings endplate, I would expect with a notched endplate, to see the pressure building up on the flap near the endplate to bleed out of the notch resulting in a drop in vortex strength. The question is the trade of in drag reduction versus the drop in pressure above the wing

[Mclaren11]

Question- What causes the air that hits the rear wing to form the small vortexes after leaving the wing? also are those the same vortexes that we see when the cars race in the rain?

[CFDruss]

Mclaren11 - As we know wings work by having a pressure difference (positive pressure distribution on one side and negative pressure distribution on the other side). With a finite wing (of a span) the pressure difference can't be maintained near the wing tips. The air will flow around the wing tip from the high to low pressure side, which creates two strong vorticies that are shed near the wing tips. The strength of the vortices are directly related to wing lift. These vortices can still occur with the use of end plates as the end plates do not extend far enough to prevent the formation of the vortices completely.
The combined effect of the two vortices is to induce an upwash (when in the context of race car wings) between the vortices and so reducing the downforce produced.
These vortices also increase drag.

Russ

[CFDruss]

Geometry: This rear wing is known by many F1 sites, and was produced a whole ago, unfortunately the designer is not known. As far as I can see the airfoil profiles are not of a published design (such as NACA). The original geometry file was very dirty and much cleaning by Keith Young was needed to ensure all surfaces edges were congruent.
From looking at a 2D view of the airfoils on this wing, it was suspect that flow separation would occur from the 2nd element. A picture of the geometry is show both in Rough_Wood's (Keith) post and below in CFX which shows a close up of the fine mesh used for analysis.

Mesh Data: Total number of Tetrahedron elements = 2,151,110
Total number of Faces = 136,696



Flow Conditions: Again, the analysis was of the wing itself and no other body members were included, therefore ignoring any body interactions with the Formula 1 vehicle. The results from analysis can therefore only be used for initial design of the wing system, and all body interactions should be included and analyzed in further design modifications. The initial flow velocity was set at 53.33 m/s (120 mph, 192 KPH). All walls of the fluid domain were set to free slip (so taking in to account ground effect) and a no-slip condition applied to the bodies surface.

Solution: Solution ran to a convergence of e-5, Time run taken = 6 hours, 52 minutes, 4.656 seconds

Results: The first image just shows roughly where the planes that many of the pictures refer to are on the geometry. I think the most obvious signs from these plots is the huge stalling of the 2nd element of the wing. Also large vortices are formed, however I can imagine these would be completely different when the wing is modeled on the car itself as the wheels and body would influence the flow streams

Results write up yet to be completed!!!!! Ran out of time!!!!

Force Data: Downforce = 461.511 N, Drag = 99.1276 N, Pitch = 453.616 Nm

[pabs]

Hey Russ,

Could you please show the vorticity field for your calculations?

Thanks

[PaulC]

So this post has taken me way too long in th making. Big thanks to Rough_Wood for the CAD and CFDRuss for the CFD insight!

First thing: Pabs, which vorticity field are you looking for? In 3D you can choose from each of the dimensions (i.e. there is vorticity in the flow direction when the flow is turning around the wing) I'm guessing you are looking for slices perpendicular to the flow direction behind the foil?

Some images/results to confirm CFDRuss. Done in FLUENT
BTW nice machine you are working with CFDRuss! I max out at 800k cells so getting the mesh size down was the toughest part for me.

inlet: 62.22 m/s downforce:~650N drag:~140N
(I left the exact numbers at work)
Compared to CFDRuss +20% velocity results in +40% downforce and drag (L/D ratio stays the same)

Static Pressure and Surface Pressure contours are similar



I suspect that the protruding edge is actually supposed to induce and control the vortex generation. This probably makes more sense with the wheel there. This also matches the vortex genration from the Monarch Formula SAE team video mentioned.

I think the cutout makes sense for slightly incident flows (i.e turns). That's probably an interesting thing to compare.

Way to cool and fun, and not enough time or CPU/memory available!

Cheers,
PaulC

[PaulC]

I wanted to add this picture in reponse to Pabs inquiry about the vorticity field.




These are contours of x-vorticity (x is the flow direction) shown at several slices (on and downstream). It is interesting how the vortex from the side tab combines with the vortex coming over the top of the end plate. Dues this help performance? I don't know.

I'm thinking of an experiment along the lines of comparing with and w/out the side tab, with and w/out an end plate notch, and straight flow versus incident flow would be useful. Unfortunately, 3 factors at 2 levels each means 8 runs to see all the effects with interactions. It is must be tough for the teams (that use CFD) to prioritize and manage the workflow, I guess that's where the expertise and the big workstation/clusters comes in.

Cheers,
PaulC

[pabs]

You're right, I should have been more explicit. I was in fact interested in streamwise vorticity to see the evolution of those vortices. Don't know if the interaction of the vortices increases performance. In general, the interaction between 2 vortices tends to dissipate them, which in principle should increase the pressure behind the wing and reduce pressure drag. But this is just a guess...