F1 2017 Aerodynamics and Car Development

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variante
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Re: F1 2017 Aerodynamics and Car Development

Post by variante » Sat Apr 28, 2018 1:31 pm

Vanja #66 wrote:
Fri Apr 27, 2018 5:23 pm
variante, I think floor sealing has more to do with keeping front tyre wake away from floor and diffuser, than with ground-effect sealing. Diffuser and ground effect floor don't work in the same way, so I never understood why teams seal them until I found out how important it is for them to keep turbulent, low-energy air away from the rear. As you car has completely closed wheels, there is no need for this - which is most likely why in WEC we don't have this floor sealing as well. :)
But the amount of turbulent flow that could potentially go under the floor of an F1 car or an LMP car is similar. The main disadvantage of an open wheeler is the turbulent flow that runs over the sidepods and goes to the rear.

I suspect the actual difference is just about design philosophies and regulations constraints. It looks like F1 teams care more about floor leading edge downforce, rather than diffuser downforce. It would make sense especially considering how small an F1 diffuser is in comparison with an LMP diffuser.

Speaking of design philosophies and floor sealing: have a look at the 2017 LMP1 Porsche, and then to the 2018 Porsche LM tribute. The former has rounded edges to let airflow in and to exploit the diffuser imposed by the FIA. The latter has skirts to achieve the exact opposite, possibly because of a different diffuser design (different car philosophy for sure).

BTW I'm not saying that there is no floor sealing in F1. I don't know for sure yet. I'm saying they focus more on the floor leading edge area.


CAEdevice wrote:
Fri Apr 27, 2018 9:13 pm
I would like to know your opinion about the cuts on the sides of the floor I have seen on the Mclaren. Something like that is present on Variante's car.
Yeah, as it's been said, their first effect is generating downforce just like a wing or a flap; the floor features either a lot of outwashing airflow with small pressure differential (so the cut acts like a wing) or a lot of pressure differential with some outwashing air (so the cut acts like a flap). At the end, there is no actual difference between the two, but you can see the different working principles: the former closer to the bargeboard and its outwash, the latter more rearwards, were the top of the floor is pressurized thanks to sidepod downwash.

As for its consequences on vortices, I'm not sure. I suspect that, if there are indeed sealing vortices along the edge of the floor, the cut we're talking about would increase its strenght and its downwashing effect.

Vanja #66
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Re: F1 2017 Aerodynamics and Car Development

Post by Vanja #66 » Sat Apr 28, 2018 1:59 pm

variante wrote:
Sat Apr 28, 2018 1:31 pm
BTW I'm not saying that there is no floor sealing in F1. I don't know for sure yet. I'm saying they focus more on the floor leading edge area.
Well, you can't cay that's not because of more open rules in front of floor leading edges :D

As for floor sealing, a year ago I was unconvinced about it, until some time ago - when I took some time to study flow viz from Red Bull RB13 Ferrari-like side pod deflectors. At that point, a lot of stuff from before that didn't make sense - started to make a lot of sense.
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variante
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Re: F1 2017 Aerodynamics and Car Development

Post by variante » Sat Apr 28, 2018 2:00 pm

As a complement to my previous post, about floor cuts:
Image
Red high pressure, blue low, orange somewhere in the middle.
You can see the big outwash close to the bargeboards, and the big pressure differential closer to the rear wheel.

Not sure what happens at the trailing edge of the cut closer to the bargeboard (which has a raised trailing edge). Does dynamic pressure win? or maybe static? Does is create a standalone vorticity or it has something to do with the sealing vortex? Is that effect strong or F1 cares more about direct downforce production?

I will find out during the next days, hopefully.

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Re: F1 2017 Aerodynamics and Car Development

Post by godlameroso » Sat Apr 28, 2018 2:56 pm

variante wrote:
Sat Apr 28, 2018 1:31 pm
Vanja #66 wrote:
Fri Apr 27, 2018 5:23 pm
variante, I think floor sealing has more to do with keeping front tyre wake away from floor and diffuser, than with ground-effect sealing. Diffuser and ground effect floor don't work in the same way, so I never understood why teams seal them until I found out how important it is for them to keep turbulent, low-energy air away from the rear. As you car has completely closed wheels, there is no need for this - which is most likely why in WEC we don't have this floor sealing as well. :)
But the amount of turbulent flow that could potentially go under the floor of an F1 car or an LMP car is similar. The main disadvantage of an open wheeler is the turbulent flow that runs over the sidepods and goes to the rear.

I suspect the actual difference is just about design philosophies and regulations constraints. It looks like F1 teams care more about floor leading edge downforce, rather than diffuser downforce. It would make sense especially considering how small an F1 diffuser is in comparison with an LMP diffuser.

Speaking of design philosophies and floor sealing: have a look at the 2017 LMP1 Porsche, and then to the 2018 Porsche LM tribute. The former has rounded edges to let airflow in and to exploit the diffuser imposed by the FIA. The latter has skirts to achieve the exact opposite, possibly because of a different diffuser design (different car philosophy for sure).

BTW I'm not saying that there is no floor sealing in F1. I don't know for sure yet. I'm saying they focus more on the floor leading edge area.


CAEdevice wrote:
Fri Apr 27, 2018 9:13 pm
I would like to know your opinion about the cuts on the sides of the floor I have seen on the Mclaren. Something like that is present on Variante's car.
Yeah, as it's been said, their first effect is generating downforce just like a wing or a flap; the floor features either a lot of outwashing airflow with small pressure differential (so the cut acts like a wing) or a lot of pressure differential with some outwashing air (so the cut acts like a flap). At the end, there is no actual difference between the two, but you can see the different working principles: the former closer to the bargeboard and its outwash, the latter more rearwards, were the top of the floor is pressurized thanks to sidepod downwash.

As for its consequences on vortices, I'm not sure. I suspect that, if there are indeed sealing vortices along the edge of the floor, the cut we're talking about would increase its strenght and its downwashing effect.
I don't think you're far off the mark at all, leading edge low pressure will "suck" upstream airflow, and further energize the diffuser, the effect is synergistic. Doubly so if the low pressure air is fenced in by vortecies along the floor. The fact the body above the floor is an air anchor further reinforces this point. The greater the mass off air is forced under the car the faster that mass will accelerate(due to constrained volume), if it can accelerate into the diffuser all the better. The tires aren't just slowing down that nice high velocity air mass and disturbing it, making it go in places where it's not wanted, or doesn't help. So all these little bastard wings and floor slots are to manage that as best as possible.

The good aero guys know how to use the tyre to their advantage they can find that little sweet spot where the tire is helping your floor sealing vortecies instead of ruining everything it interacts with.

The Williams has huge problems with turn in instability, which means that under initial yaw the car loses downforce, likely due to negative interaction with the tires and the diffuser. Fixing it isn't as simple as a floor tweak, it takes work upstream as well.
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