W06 Influenced CFD Study

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miqi23
7
Joined: 11 Feb 2006, 02:31
Location: United Kingdom

Re: W06 Influenced CFD Study

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Any chance you can plot static pressure coefficient over the surfaces of your wing instead of static pressure? Top and bottom surfaces if you could please?

Just quickly read the whole thread, are your wing profiles Okish to start with?

bhall II
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Joined: 19 Jun 2014, 20:15

Re: W06 Influenced CFD Study

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chuckdanny wrote:Its not that far off, its bhall that is trickering with perspective :mrgreen:
There must have been something in my eyes earlier, because the wing looks quite different to me now.

Image

Still lacking: the "arches" should be curved inward at the bottom, not straight; the rear-most "arch" needs Gurney flaps along the top and outside edges; the cascade support is affixed to the wrong "arch"; the footplate slots are not representative (they're also ilegal, because the cutouts extend below the reference plane); and the vertical turning vane needs to be tapered toward the top.

Other than that, this car-less wing will clearly produce meaningful results.

chuckdanny
69
Joined: 11 Feb 2012, 11:04

Re: W06 Influenced CFD Study

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Still lacking: the "arches" should be curved inward at the bottom, not straight
It is
Image
the cascade support is affixed to the wrong "arch"
It isn't
Image
It hangs over the 1st, no need to fixe it, it doesn't really move, i don't intend to model fluid structure interaction.
the rear-most "arch" needs Gurney flaps along the top and outside edges
Like the old version? It comes after multibody merging.
Any chance you can plot static pressure coefficient over the surfaces of your wing instead of static pressure?
It is used to compare different scales no? You've got wind tunnel datas ?

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RicME85
52
Joined: 09 Feb 2012, 13:11
Location: Derby
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Re: W06 Influenced CFD Study

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chuckdanny wrote:
Still lacking: the "arches" should be curved inward at the bottom, not straight
It is
Image
Through my eyes the actual arch is more scooped than yours

bhall II
473
Joined: 19 Jun 2014, 20:15

Re: W06 Influenced CFD Study

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Image

chuckdanny
69
Joined: 11 Feb 2012, 11:04

Re: W06 Influenced CFD Study

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Yes this feature in general of a rounded bottom outer part of arches may be important. My model is so well constructed that it shouldn't be a problem to modify :D

eyalynf1
6
Joined: 24 May 2011, 01:05

Re: W06 Influenced CFD Study

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bhall II wrote:Oh, boy.
chuckdanny wrote:THe wheel is not turning much but for very slow corners. Yaw angle is 5° at max i heard would this change the vortex state?
I'm not saying you're wrong i'm skeptical (ok let's say i'm more diplomat :lol: ).
Have we really gone this whole time without it being patently clear that addressing the above issue is the central tenant to my theory? Here's a refresher, if you like.

Things to note as you move forward:

Try to keep it in mind that you're not actually testing this car...

http://i.imgur.com/8AOUgGw.jpg

...you're testing this "car," and the data will reflect it.

http://i.imgur.com/UyFW6dO.jpg

Context is everything...
Yeah, I've got to upvote this! So funny...

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henry
324
Joined: 23 Feb 2004, 20:49
Location: England

Re: W06 Influenced CFD Study

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@chuckdanny. First thank you for a fascinating thread. Through your efforts, and also @bhall II's commentary, I have gained a real appreciation of the sort of things going on at the front of an F1 car. I say appreciation because I would not claim to understand.

Since you are currently talking about a lot of details have you included the effect of rake on the geometry of your model? I don't have any accurate figures but I would hazard a guess at an increased angle of attack by maybe 1 degree and that the leading edge would be, perhaps, 15 mm down at static and somewhat more at speed as the T tray approaches the ground.
Fortune favours the prepared; she has no favourites and takes no sides.
Truth is confirmed by inspection and delay; falsehood by haste and uncertainty : Tacitus

Just_a_fan
591
Joined: 31 Jan 2010, 20:37

Re: W06 Influenced CFD Study

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As bhall is pointing out, there are so many differences between the real and modelled wings that it's not surprising to see some "odd" results - such as the direction of flow inside the wheel. It's an excellent model, we're all agreed, but these small difference can have big effects - after all, that's why the teams spend so much time making small changes in the first place!
If you are more fortunate than others, build a larger table not a taller fence.

chuckdanny
69
Joined: 11 Feb 2012, 11:04

Re: W06 Influenced CFD Study

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But just_a_fan, you did learn something here for example no ?
I'm minded to remember the video of the butterfly going through the upper turning vanes on the Lotus. The acceleration across the front, and outboard of, the front tyre was very marked. That isn't going to be an isolated flow structure. I note that this sort of flow isn't obviously identified in this study which suggests that we're missing some detail that matters.
I don't think that this study is missing something regarding this pattern :
That the butterfly crossing the 2 rolling vortices (under the axes) created on the back face of the turning vanes was ejected outboard because of it being on 2nd floor not obviously because such small turning thing could deviate like a bent laminar flow horizontal column forming a river turning outside the wheel. The endplate Contra rotating vortex acting as a relay.
What would have happen if it were on the 3rd floor? Just above the max height of the wing, above the turning vane vortices?
Particule trajectories in a flow is not streamlines !

For the arches vortex acting as drag reduction system when bursting on the tire tread, was is not one of my early assumption?
It is confirmed by the Perinn workshop, you should have a look:
https://www.youtube.com/watch?v=CjjYtmI ... e=youtu.be

The inflow pattern is present too with the gutter and arches vortices acting as one.

chuckdanny
69
Joined: 11 Feb 2012, 11:04

Re: W06 Influenced CFD Study

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The combination of merging turning vane vortices (inside of the tire) and contra rotating upper edge endplate vortex outside of the tire (feeded by the contra contra rotating hence co rotating with regard to the turning vanes ones or 2 merging in two one, i understand myself) create an upwash just ahead of the wheel, do you hear that ? This vortex system is a way to move up the flow in front of the wheel for the sake of reducing drag, adverse flow structures behind the wheels etc..

You should do the analyses guys, i'm the modeler, the artist !
Image

@henry
The effect of rake is essentially increasing ground effect.
Last edited by chuckdanny on 24 Jun 2015, 23:01, edited 1 time in total.

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hollus
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Joined: 29 Mar 2009, 01:21
Location: Copenhagen, Denmark

Re: W06 Influenced CFD Study

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Do you mean like this?
Image
Rivals, not enemies.

chuckdanny
69
Joined: 11 Feb 2012, 11:04

Re: W06 Influenced CFD Study

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What is this? it can't be legal ? Like this but in a very different subtle manner and with outwash on both sides.

In the explanation above, the plenum behavior of the slotted footplate upper path would make sens (thanks bhall for the vocabulary i didn't know the word) feeding arches, turning vanes and upper endplate edge contra rotating vortices, the surplus leaking outside and feeding the outside winglet vortex flowing along the outside tire bottom flank interacting etc...

And the canard ? It is there to protect the upper EP edge vortex birth ! Highly favored by turning vane crossflow.
Last edited by chuckdanny on 24 Jun 2015, 23:09, edited 1 time in total.

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hollus
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Joined: 29 Mar 2009, 01:21
Location: Copenhagen, Denmark

Re: W06 Influenced CFD Study

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That's an illegal wing for testing, I just wonder if it is testing in the rear wheels what you just described that (maybe) is happening in front of the front wheels.
Rivals, not enemies.

bhall II
473
Joined: 19 Jun 2014, 20:15

Re: W06 Influenced CFD Study

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chuckdanny wrote:I don't think that this study is missing something regarding this pattern :
That the butterfly crossing the 2 rolling vortices (under the axes) created on the back face of the turning vanes was ejected outboard because of it being on 2nd floor not obviously because such small turning thing could deviate like a bent laminar flow horizontal column forming a river turning outside the wheel. The endplate Contra rotating vortex acting as a relay.
What would have happen if it were on the 3rd floor? Just above the max height of the wing, above the turning vane vortices?
Particule trajectories in a flow is not streamlines !

For the arches vortex acting as drag reduction system when bursting on the tire tread, was is not one of my early assumption?
It is confirmed by the Perinn workshop, you should have a look:
https://www.youtube.com/watch?v=CjjYtmI ... e=youtu.be

The inflow pattern is present too with the gutter and arches vortices acting as one.
I'm continually astounded by your inclination to draw even the slightest of conclusions from this.

In what universe is this true: flawed, incomplete model + flawed, incomplete simulation = perfectly logical outcome?

Image
Civil engineering by chuckdanny

Also from Nic Perrin...
Q&A with Nic Perrin wrote:One user said that he would expect the flow to be symmetric. So why is it not symmetric? Because he saw some non-symmetric structures.

Perrin: I have to say, that person is a very good observer. But first of all, to develop the car, we try to run a full car, purely because there are quite a lot of tests when we put steer angle on the car just to simulate different conditions. So obviously we need a full car for these, so we [attempt] to use a full car all the time which obviously needs a lot more completing power. But the other thing is that the asymmetric structure of the flow comes from the fact that purely the modern wind tunnel has slightly different flow. Because you find that the convergence is not always going to the same states, especially near the wheel compact parties. And that in itself creates an asymmetric. But it’s quite realistic because you have to know that the flow is not static, even though if we are simulating a steady static flow, it’s obviously the turbulence which then creates these sorts of differences. Which is another reason for simulating a full car, because you end up with an average false, basically you simulate twice the same model, and that gives you a better average answer, if that makes sense.
I understand that, as "the modeler, the artist[e]," you're not necessarily concerned with "knowing what you're doing." But, you really ought to take a gander at this proper study of wing/wheel interaction. Though it may indeed put you to sleep a few times, maybe you'll nonetheless absorb some information through digital osmosis.

Until then, you might want to really think about the logic of reducing the surface area available to create downforce in order to somehow reduce drag...

Image

...when the single-largest contributor to drag is frontal area, which doesn't change.

Image

And I bet you'd see any "plenum-like" behavior in your model stop quick, fast, and in a hurry if you corrected the spacing and angles of attack of the "arches."

Image

EDIT: Nevermind
Last edited by bhall II on 25 Jun 2015, 08:37, edited 2 times in total.

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