2017-2020 Aerodynamic Regulations Thread

[rileykirn]

Question for the aero guys regarding the 2017 rules: Would it be possible, per the rules, to leave a space between the bottom of the sidepod & the top of the floor, from the tub/engine out? The sidepod would therefore be mounted to the tub/engine & there would be a channel for air beneath the tub intake above the floor(all the way from outer edge of floor to the tub vs the existing undercut of the sidepod)? My thought is that air would be split in three areas there. (1)Below the floor to feed the diffuser, (2)between floor/diffuser & sidepod & then(3) the sidepod intake. The thought would be that more air in this section could then be manipulated(say sped up or conditioned via vortex generators) to effect the flow of the diffuser exit air vs trying to keep it attached around the undercut of he sidepod.

This has been done in recent past; not sure of its benefits

https://encrypted-tbn2.gstatic.com/imag ... UHbsSZh7SC

Interesting. Thanks for the pic.

[rileykirn]

Maybe it raises the center of gravity too much & I'm sure it would be a packing challenge.

[bhall II]

Maybe it raises the center of gravity too much & I'm sure it would be a packing challenge.

My theory is that it reduces downforce.

Static pressure (downforce/lift) is highest where dynamic pressure (velocity) is lowest. Naturally, the inverse is also true.

The fronts of the sidepods slow down air flow over the floor...



...and bargeboards, diffusers, etc., accelerate flow under the floor.

If static pressure on top of something is higher than static pressure below it, the pressure differential is indicative of downforce. A design that allows faster air flow over the floor would reduce that pressure differential, ergo it would reduce downforce.

[wuzak]

Surely it is to try to get more air over the top of the diffuser, gaining downforce that way?

[bhall II]

This is one of the exceedingly rare cases in which it's entirely possible to have your cake and eat it, too. We touched on it a couple of weeks ago.

To move air flow around the sidepod, you use a flip-up (or two) on the "horn"...

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

...to create a vortex that will (hopefully) elevate air flow that's not been directed under the floor. From there, the low-pressure wake created by the angled, lower section of the turning vane will pull the elevated air flow inward, toward the car, positioning it to be accelerated around the Coke bottle area by the low-pressure wake left by the sidepod...

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

To add context, I think the relative lack of that design characteristic is probably why Williams' chassis have lately been celebrated for their top speed and not much else.

[gavingav1]

2017 ferrari according to Autosprint

[PlatinumZealot]

The 2017 cars will all look the same for reals. Regs too tight.

I been reading some of the pasts a few pages back. I don't want to get into the whole outwash inwash thing too much as it was heavily discussed in 2009, but i want to say that these present day wings, if you just look at them, have elements of outwash and "overwash" plus upwash. There is a also a strong tendency to create two main vortices inboard of the front wheel. I will not call this inwash becaus thes flow structures are not "forced" in that inwash direction.
Buy let us be clear that the outwash element is not as strong as it used to be. Teams are making better use of that energy for creating vortices that flow inboard of the wheel.

[rjsa]

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

It's through vortex lift that delta-winged aircraft are able to operate at high angles of attack, since vortices shed along the leading edge keep air flow attached to the low-pressure side of the wing. Other aircraft, mostly fighters, use leading edge extensions to create the same effect.

You answered your own question: vortex lift happens when the aircraft is doing extreme 3D maneuvering - what causes the leading edge of the wing to operate at high AOAs. In a racing car that AOA vary by the pitch angle, and that's limited to a few degrees.

[godlameroso]

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

It's through vortex lift that delta-winged aircraft are able to operate at high angles of attack, since vortices shed along the leading edge keep air flow attached to the low-pressure side of the wing. Other aircraft, mostly fighters, use leading edge extensions to create the same effect.

You answered your own question: vortex lift happens when the aircraft is doing extreme 3D maneuvering - what causes the leading edge of the wing to operate at high AOAs. In a racing car that AOA vary by the pitch angle, and that's limited to a few degrees.

What about roll and yaw? Have you seen how much the 2016 Mercedes rolled in the corners? In planes roll causes some yaw, in a plane you roll into the turn, but F1 cars have their wings upside down, so rolling away from the turn creates yaw towards it.

[bhall II]

You answered your own question: vortex lift happens when the aircraft is doing extreme 3D maneuvering - what causes the leading edge of the wing to operate at high AOAs. In a racing car that AOA vary by the pitch angle, and that's limited to a few degrees.

The scope for vortex lift isn't necessarily confined to transient events; that's just how it tends to apply to aircraft.

But, like I said, the delta wing example was a bad one. This is more closely aligned with my thoughts...

Controlled Separated Flow or Leading Edge Vortex Flow. This is a half-way stage between steady streamline flow and unsteady flow described later. Due to boundary layer effects, generally at a sharp leading edge, the flow separates from the surface; the flow does not then break down into a turbulent chaotic condition but, instead, forms a strong vortex which, because of its stability and predictability, can be controlled and made to give a useful lift force. Such flows are found in swept and delta planforms particularly at the higher incidences.

Something else to consider is that AoA essentially just describes a pressure gradient. Given a strong Y250 vortex, for instance, you can create a useful pressure gradient without extreme AoA. The only question is whether or not the sweep angle will be sufficient to take advantage of it. If it is, the neutral center section of the wing can be rendered "neutral" in name only.



...or so goes my thought process.

[godlameroso]

If it does it could mean the front wing philosophy will change seeing as we're moving away from a flat leading edge. Meaning your proposed leading edge vortex(due to the leading edge sweep of the wing) may not interact properly with the rest of the wing if the same end plates and cascades are used.

[bhall II]

Individual elements have been swept for years, which means swept wings don't necessarily represent a sea change in thinking. The shift is certainly no greater than what we saw in 2009.

Taking a step back for a moment...

What about roll and yaw? Have you seen how much the 2016 Mercedes rolled in the corners? In planes roll causes some yaw, in a plane you roll into the turn, but F1 cars have their wings upside down, so rolling away from the turn creates yaw towards it.

This is sorta maybe applicable insofar as it's theoretically possible to exploit such characteristics.. However, what you've described is pitch sensitivity, and teams generally try to avoid it, because the level of control needed to make it favorable would be very difficult to achieve, even by F1 standards. (Think about what happens downstream.)

[godlameroso]

I have, the rear end particularly the floor is affected by the front but the rear wing, and airflow over the side pods gets mostly unconditioned air. The difficulty would be channeling the vortices from the front end to the rear end under various roll and tire slip angles.

In any case it seems like it's more effective to minimize pitch but allow roll, or that roll by itself is not as detrimental to aero as it appears.

[bhall II]

In the context of an inverted airfoil in ground effect, what we call "pitch sensitivity" would probably be better represented if we called it "ride height sensitivity" instead, because ride height is far and away the most influential factor.

What mitigates the impact of transient ride height changes in roll, at least as far as the front wing is concerned, is the fact that downforce always acts upon the chassis through the nose, regardless of where it's generated on the wing. That means there's little to be gained through those variables specifically.



I'm not exactly sure what you mean by channeling vortices or unconditioned air flows. But, I'd just like to point out that managing sidepod air flow is an area of active development.

In a way, the more air flow you can route around the sidepods, the less you have to deal with the lift created by air flow over them, if that makes any sense...



Incidentally, this is yet another area in which aerodynamacists and the "specialized press" have taken everyone for a ride. Remember "downwash" from the Coanda era?

[Tommy Cookers]

there's no magic beans related to wing sweep, despite Mr Pathirana's blog

eg forward swept wings have been used even quite recently because of the limitations of conventional sweep on attachment
vortex lift could be called induced drag lift ie it's inevitable but increases with low aspect ratio and related higher AoA capability and need

and our Re Nos are significantly disadvantageous to attachment