2017-2020 Aerodynamic Regulations Thread

[godlameroso]

McLaren's Tim Goss:


Not a lot of the renders of 2017 cars we've seen so far show the "curviness".

How will teams interpret this curviness ?? How strict are the rules in this regard ??

Any ideas Aero Guys ??

Surprised you didn't quote this part

"A lot of the flow structures and physics on the car are fundamentally the same, how the flow is established at the front of the car and then travels back down the car, starts off in a fairly similar way to last year.

“Now what you’ll find is that, in the detail, things start to behave differently, which prompts you to change direction. The 2017 cars will look pretty similar to the layman, but the aero guys have been battling to correct flow-structures at different ride heights for months and months now. We’ve had to rethink lots of different areas on the car, because they’re behaving differently to how they did before.”

Also we'll see some P1 inspired barge boards, nice wavy multi element designs.

http://www.thecheckeredflag.co.uk/wp-co ... 40x760.jpg

I haven't been able to suss out which regulations define the new bargeboards. If there is any wording similar to the RW endplate regulations, for example a surface area limit when viewed from above. If there is, then the depictions we've seen of a thin, sheet-like part might be accurate predictions.

FWIW these are the legality volumes, you can fit whatever you want below the green box on the profile view, and anything inside the green box on the plan view



As well as everything that's behind the green box in this image

[wuzak]

If you wanna get really outlandish, sometimes I wonder if the idea behind giant brake ducts is less about cooling the brakes and more about either delaying separation when cornering (more downforce) or reducing the steering angle change necessary to unblock the wing (more consistent downforce).

http://i.imgur.com/E1QWd9t.jpg

I believe the Ferrari pictured had hollow front axles, and much of the air that went into the duct exited to the outside of the wheel.

It certainly should help your theory about outwash on the outside side of the car in a corner.

[roon]

Surprised you didn't quote this part

"A lot of the flow structures and physics on the car are fundamentally the same, how the flow is established at the front of the car and then travels back down the car, starts off in a fairly similar way to last year.

“Now what you’ll find is that, in the detail, things start to behave differently, which prompts you to change direction. The 2017 cars will look pretty similar to the layman, but the aero guys have been battling to correct flow-structures at different ride heights for months and months now. We’ve had to rethink lots of different areas on the car, because they’re behaving differently to how they did before.”

Also we'll see some P1 inspired barge boards, nice wavy multi element designs.

http://www.thecheckeredflag.co.uk/wp-co ... 40x760.jpg

I haven't been able to suss out which regulations define the new bargeboards. If there is any wording similar to the RW endplate regulations, for example a surface area limit when viewed from above. If there is, then the depictions we've seen of a thin, sheet-like part might be accurate predictions.

FWIW these are the legality volumes, you can fit whatever you want below the green box on the profile view, and anything inside the green box on the plan view

https://albrodpulf1.files.wordpress.com ... 201713.jpg

As well as everything that's behind the green box in this image

https://albrodpulf1.files.wordpress.com ... 201725.jpg

Good post. They're gonna go crazy in that area if those drawings are correct. Seemingly there's nothing to prevent them from pushing the leading edges of the sidepods & the floor forward. Maybe also some big ramps or trumpets which lead under the floor.

I'm reminded of RB's suspension arm rumors. Given the proximity of the free zone (the second image I think illustrates its boundaries better), maybe the trailing arms link up with or are incorporated into this whole complex.

[bhall II]

I believe the Ferrari pictured had hollow front axles, and much of the air that went into the duct exited to the outside of the wheel.

It certainly should help your theory about outwash on the outside side of the car in a corner.

That's more or less how I see it as well. I guess where my interpretation differs from the accepted narrative is that I tend to think blown axles don't have much to do with anything downstream. What makes less sense as a tool to shape wheel wake, for instance, makes a whole lot of sense as a way to control an edge vortex (C) ...



If so, it acts a bit like a vacuum that delays separation by reducing the adverse pressure gradient along the suction surface of the wing, which then allows a higher angle of attack for more downforce. It also minimizes the steering angle change necessary to unblock the endplate, and that increases yaw rate, aka the single most important aspect of F1 aero design. And it certainly doesn't hurt matters that it cleans up aero between the wheels.

(Note: that wing is not representative of F1. It's from a paper that explores wing-wheel interaction.)

For me, the (suspected) dead giveaway is that teams who run giant brake ducts do so even at Monza, where accepted explanations suggest it would be unnecessary, if not detrimental.




EDIT: Here's a composite image I put together last year using CFD from an analysis of MP4-29's front wing...



Since I'm not entirely sure if the front wheels were factored into the simulation - I suspect not - that may or may not be indicative of real-world flow structures. Also, the colors are completely irrelevant to the discussion, because they don't depict relative velocity, pressure, or anything of the sort. In any case, it's a decent illustration of front wing endplate vorticity in general and how it could conceivably interact with the brake ducts.

EDIT 2: This is immediately my favorite F1 aero analysis of all time.

Despite clear evidence that goes against the widely-held assumption that blown axles serve to manage wheel wake, the author still concludes that the goal is to manage wheel wake.

On upper part of the picture dirty air behind front wheel without blown front axle.
On the lower part of the picture disturbances behind wheel with blown front axle are different, wake behind the front tires is reduced, air is much cleaner with less turbulences and sidepods entrances flow is less disturbed

What I see is a device that apparently increases drag and deposits wheel wake exactly where it's not supposed to be.

[Just_a_fan]

http://i.imgur.com/ZFWVmbT.jpg
Since I'm not entirely sure if the front wheels were factored into the simulation - I suspect not - that may or may not be indicative of real-world flow structures. Also, the colors are completely irrelevant to the discussion, because they don't depict relative velocity, pressure, or anything of the sort. In any case, it's a decent illustration of front wing endplate vorticity in general and how it could conceivably interact with the brake ducts.

That study was looking at the effect of the cacade winglets and the under wing strakes on air flow. What the bit you've copied does show is that the cascade winglets create a defined flow around the inside of the front wheel. I would expect that this flow is further finessed by devices on the inside face of the upright - vortex generators in the case of the Mercedes you've used. Other cars may use big brake ducts and hollow axles to duct this same air outwards to some degree as you've surmised.

Unfortunately the study didn't factor in the front wheels but it is not unreasonable to think that cascade winglets are there to control flow around the front wheel based on their geometry and position.

I'm reminded of the flow conditioners used on the MP4-23 (amongst others). The nose hoop was all about setting up the flow downstream rather than making downforce in its own right.

[bhall II]

Unfortunately the study didn't factor in the front wheels but it is not unreasonable to think that cascade winglets are there to control flow around the front wheel based on their geometry and position.

Maybe. I wasn't really trying to say anything about cascades; I just wanted something that illustrates general trends.



That said, you might not need oversized brake duct inlets to achieve the desired effect if you're willing to sacrifice a bit of the front wing's surface area in order to allow for wider endplates (in this context, some folks call them "vortex tunnels").

[Just_a_fan]

I just wanted something that illustrates general trends.

A good intention, no doubt, but we have to be careful that we don't try to compare apples with oranges. Taking info from one issue and trying to fit it to another one is likely to lead us down blind alleys.

But at least we're trying to have a technical discussion rather than fan-wars, so we should applaud ourselves for that. =D>

[Just_a_fan]

http://i.imgur.com/Li8yNr5.jpg
On upper part of the picture dirty air behind front wheel without blown front axle.
On the lower part of the picture disturbances behind wheel with blown front axle are different, wake behind the front tires is reduced, air is much cleaner with less turbulences and sidepods entrances flow is less disturbed

What I see is a device that apparently increases drag and deposits wheel wake exactly where it's not supposed to be.

I've been wondering about this. I assume, perhaps wrongly, that the air discharged by the wheel nut will have a higher vorticity at higher car speeds. If this is the case, could the wheel nut discharge's effect be speed sensitive? That is, could the vortex produced be intended to interact with the floor at higher speeds and thus reduce downforce and thus drag?

Just turning over an idea here, not sure if it's feasible.

[bhall II]

No need to worry about blind alleys here - famous last words. An inverted airfoil in ground effect will always generate vorticity as high-pressure air flow is pulled under the wing.



If allowed to fully develop, the resultant vortex will always be entrained along the endplate at the point of peak suction.



Maybe some of the confusion is a bit semantic, and if so, I'm as guilty of perpetuating it as anyone else.

In most cases, the thing we call an "endplate" isn't. Functionally, the real endplate is inside the "endplate."



(In reality, the blue air flow in front of the wing will encompass the entire wing. I just can't figure out a way to draw it that doesn't look like ---.)

With regard to the blown axle, I don't know enough to really riff on it one way or the other. All I know is that the explanation typically spewed by the "specialized press" is mindless.



The "void" behind the wheel equipped with a blown axle is Drag City, because wheel wake will recirculate into it such that air flow behind the wheel will be moving forward faster than the car. That creates an unsteady nightmare...





Source: Grip or Aerodynamics: The Fluid Mechanics of Formula 1 Wheels

In a way, a packet of recirculated air in that situation is a bit like Pastor Maldonado, since it will crash into everything because it can't overtake anything.

[Just_a_fan]

No need to worry about blind alleys here - famous last words. An inverted airfoil in ground effect will always generate vorticity as high-pressure air flow is pulled under the wing.

https://www.youtube.com/watch?v=9VROxz0g5Vw

If allowed to fully develop, the resultant vortex will always be entrained along the endplate at the point of peak suction.

http://i.imgur.com/RxYH0KO.jpg

I think the design of the end of the wing (what is popularly called the endplate) is trying to use that resultant vorticity in two ways. One is generate downforce. The other is to control / cajole the dirty air behind the front wheel. Use that vortex on the outside of the wheel to pull the tyre squirt away from the leading edge of the floor. The bargeboard then deals with cleaner air giving improved leading edge downforce as well as diffuser link downforce.

It's difficult to know either way without access to some real data.

Maybe some of the confusion is a bit semantic, and if so, I'm as guilty of perpetuating it as anyone else.

It's always an issue when laymen talk about a technical subject. We're all guilty.

The "void" behind the wheel equipped with a blown axle is Drag City, because wheel wake will recirculate into it such that air flow behind the wheel will be moving forward faster than the car. That creates an unsteady nightmare...

Which is why so much work is done in the outer portion of the front wing. It's all about tidying up that flow and keeping it outboard as much as possible. I'm trying to find the image of the Mercedes from above in the wet. The spray is obviously being diverted outboard behind the wheel. Not just caused by the front wing, of course.

https://www.youtube.com/watch?v=-E2XDdihxh4

https://www.youtube.com/watch?v=UsuQVLx9lFY

Nice vids, good to see them again. =D>

In a way, a packet of recirculated air in that situation is a bit like Pastor Maldonado, since it will crash into everything because it can't overtake anything.

[bhall II]

It's difficult to know either way without access to some real data.

That's why I posted some real data yesterday.

Think about it: what is the root cause of wheel wake turbulence?



Doesn't it seem like a good idea to direct air flow around the wheel asymmetrically in order to counter the oscillation?



(Naturally, there's more to it than that.)

[godlameroso]

Well for one you're not allowed to have brake ducts on the outside of the wheel, that would make your front wing look totally different though.

There's so much freedom with the barge boards for next season, will it really be as critical to try to control front wheel wake in a similar way to what's been done? Can there be solutions that exist merely to reduce drag of the front wheels, and focus more on developing the same downforce through the barge boards? Or would conventional thinking be best for the new regulations?

Where in 2016 losing or damaging the front wing would reduce downforce by as much as 70%, with the new regulations that change is going to be at most up to 40% reduction in total downforce for damaging the front wing, given how powerful the floor and body work will become.

Regarding the blown axlex, I can only imagine it has to do with hot air being injected into the streamwise vortex.
Adding heat only strengthens a streamwise vortex, because in part heat increases the viscocity(which pulls the surrounding turbulent air more effectively into the vortex(I'm trying to keep it in laymans terms)), and mostly because heat increases the volume of air(which lowers the pressure and strengthens the vortex on it's own(a vortex is somewhat a focused coherent parcel of low pressure air(or air laser as I like to call it)).

[bhall II]

Well for one you're not allowed to have brake ducts on the outside of the wheel, that would make your front wing look totally different though.

Clearly.

This is the idea I dispute...

Which is why so much work is done in the outer portion of the front wing. It's all about tidying up that flow and keeping it outboard as much as possible.

It's not, but I'm perfectly content to disagree.

[Just_a_fan]

One useful technique when dealing with unsteady flow separation is to trip the flow where you want it. One example is the little vortex generators you see on aircraft engine pods.

It's not beyond the bounds of possibility that one or more flow structures, coming off the front wing, are intended to trip the wheel airflow separation. There is no doubt that the teams are trying to control wheel wake in some manner or other. It is a major source of the car's drag. It is also an impediment to efficient downforce production by both the front wing and the floor.

[godlameroso]

One useful technique when dealing with unsteady flow separation is to trip the flow where you want it. One example is the little vortex generators you see on aircraft engine pods.

It's not beyond the bounds of possibility that one or more flow structures, coming off the front wing, are intended to trip the wheel airflow separation. There is no doubt that the teams are trying to control wheel wake in some manner or other. It is a major source of the car's drag. It is also an impediment to efficient downforce production by both the front wing and the floor.

Mercedes did this often in the bodywork with all those serrated edges, and cheese grater barge boards.

Ferrari had serrated edges at the trailing edge of their front wing flaps as well. I remember McLaren using serrated edges on the lower edge of the upper rear wing flap.

Shark skin has small teeth like structures in place of fish scales which are wonderful at reducing drag by "tripping" the flow of water.

But fabricating that crap in carbon fiber would be a real challenge.