Diffuser functions

[marekk]

On a hot day of say 100 F, the track could get as higher as 125-130 (depending on how dark and make up of the asphalt) Putting your hand a couple of inches above the pavement you can feel the difference in the radiating heat.

Never thought about this, but speedsense found probably cheapest way to decrease parasite drag of F1 car - just paint all tarmac facing surfaces of the car black with mat finish and use heat radiated from the asphalt to maximize temp of those surfaces. Not very big deal probably, but every 0.01s counts, and the cost is basically zero.

[speedsense]

On a hot day of say 100 F, the track could get as higher as 125-130 (depending on how dark and make up of the asphalt) Putting your hand a couple of inches above the pavement you can feel the difference in the radiating heat.

Never thought about this, but speedsense found probably cheapest way to decrease parasite drag of F1 car - just paint all tarmac facing surfaces of the car black with mat finish and use heat radiated from the asphalt to maximize temp of those surfaces. Not very big deal probably, but every 0.01s counts, and the cost is basically zero.

Well, at least the black color will hide how "fat" the trailing edges of your side pods are to the pundits...at least my wife thinks this way and her liking of black pants in those times of lowered horsepower gains....

Stationary (no wind) vs moving on the car...
Actually it was your guys portion of this thread that started the thought process of it, so like my wife, I blame you for it..

[godlameroso]

I think that this year's smaller's diffusers have forced teams to create a sort of Tri-plane rear end. Bear with me for a second, I think that the rear of the car uses the diffuser as a diffuser for the floor and as a third wing. You have the main wing on top, you have the beam wing in the middle, and the diffuser/wing on the bottom. Think about it, the regulations this year were worded in such a way as to separate the flows in the rear of the diffuser and wings. So the best team is the one that improves the efficiency in these three areas. That's one of the reasons why the RB7 currently features a smaller rear wing than other teams.

Another thing that catches my attention is the ducting for the RB7, if the drawings from Scarbs are accurate, then what is happening is some hot air from the cooling system exits over part of the sidepods, the rest gets squeezed into a cavity that travels upward, into a diffuser(like one on a trumpet or an a/c vent) which then exits out over the beam wing. Basically all the hot air from the cooling system exits out by the beam wing of the car, slightly lower than this hot plume of air, is the exits for the exhausts, and diffuser. In essence you end up with a lot of relatively cooler higher pressure air, surrounding a lower pressure hot air center.

By moving as much relatively cool air out of the way with the front end, you in essence increase the pressure on the front end of the car, and decrease it on the rear end as the by-product of cooling. If that is what they are trying to acheive, then it would make more sense to try to trap that hot air center with the rear body work than it would be to try to put the diffuser as low to the ground as possible. Not that those are your only options, but just an observation.

[marekk]

Another thing that catches my attention is the ducting for the RB7, if the drawings from Scarbs are accurate, then what is happening is some hot air from the cooling system exits over part of the sidepods, the rest gets squeezed into a cavity that travels upward, into a diffuser(like one on a trumpet or an a/c vent) which then exits out over the beam wing. Basically all the hot air from the cooling system exits out by the beam wing of the car, slightly lower than this hot plume of air, is the exits for the exhausts, and diffuser. In essence you end up with a lot of relatively cooler higher pressure air, surrounding a lower pressure hot air center.

We've discussed it in more detail in FFE thread, and the conclusion is there is a LOT of thermal energy stored in exhaust and cooling air (few hundreds kW.
As the hot air quickly cools down it contracts, so the best thing you can make IMO is to position this amount of air at slow speed (exactly what the trumpet shape does) as low behind the car as possible, to help extract the air from diffuser.

[shelly]

I have tried to summarize what I have learned about floors aerodynamics in this picture.
It is a mspaint sketch of a floor in bottom view, colored with cp - pressure coefficient. It is not detailed nor precise, but I think it summarizes a lot of things, even if it has to be taken with a pinch of salt.

I represented suction peaks and vortex low pressure streaks in it.
Main vortexes from ttray, bargeboard diffuser fin and diffuser footplate can be seen.