Exhaust Blown Floor - Forward Exhaust Exit

[TURU]

[youtube]http://www.youtube.com/watch?v=oT2P2fhRFQA[/youtube]

Does anyone still have any doubts what this exhaust is trying to achieve and where it is blowing?

[Richard]

I thought we had agreed that the exhaust gasses form a layer at the outer edge that mimics skirts?????

... and that virtual skirt traps the air in front of the sidepod so it passes under the floor. The spray pics do appear to support that notion.

Having said that, marekk could you post pics of another car for comparison please? What if they all have the same spray pattern?

[marekk]

I thought we had agreed that the exhaust gasses form a layer at the outer edge that mimics skirts?????

... and that virtual skirt traps the air in front of the sidepod so it passes under the floor. The spray pics do appear to support that notion.

Having said that, marekk could you post pics of another car for comparison please? What if they all have the same spray pattern?

Sorry, but no other cars at this time, place and camera angles.

Few observations, as always pure speculation:

1. On the youtube video posted by TURU, as the car accelerates, in the bargeboard area there is clearly visible "virtual tube" exactly as predicted by shelly. This makes floor appearing lower to the flow then it really is, and adds downforce just at the leading edge.

2. Watched closely all the cars in FP1 and one pattern emerges: front tyre spray tends to go straight to rear tyre at lower speeds and goes under the car as speed increases. Almost the same for R31, but later on (and only R31 displays this knick in spray flow as seen on my pictures). Sort of virtual skirt in the rear half of the floor, when you want - more precise description will be flow lines bending in outside direction. Conservation of momentum, nothing to argue.

Adds to downforce at the rear and could decrease drag by "pushing" dirty turbulent flow outside, against diffuser's "sucking" force, just to the face of rear tyre.

3. Very different situation on breaking. Overrun used sparsely (they have to balance possible gains and added fuel weight), but when used, due to much quicker and hotter exhaust almost all goes out of the floor, in very slow corners even behind rear tyre. Should be very effective at speeds at which other area doesn't work so well, but they have to carry extra fuel to drive it.

[hollus]

I wish I had seen that FP1, well, next time it rains!

So I guess it is not about the gas going under the floor, then.

Thanks to TURU for posting that video.

[hardingfv32]

May I assume the goal is to remove air from under the side pods (using the diffuser) and/or keep it out of the area below the side pods (using virtual skirts).

Would the exhaust flowing perpendicular to the air flow help seal the entrance of the area below the side pod?

Brian

[PlatinumZealot]

Video shows everything, the CFD's by ringo were actually very accurate.

[ringo]

I thought we had agreed that the exhaust gasses form a layer at the outer edge that mimics skirts?????

... and that virtual skirt traps the air in front of the sidepod so it passes under the floor. The spray pics do appear to support that notion.

Having said that, marekk could you post pics of another car for comparison please? What if they all have the same spray pattern?

Sorry, but no other cars at this time, place and camera angles.

Few observations, as always pure speculation:

1. On the youtube video posted by TURU, as the car accelerates, in the bargeboard area there is clearly visible "virtual tube" exactly as predicted by shelly. This makes floor appearing lower to the flow then it really is, and adds downforce just at the leading edge.

2. Watched closely all the cars in FP1 and one pattern emerges: front tyre spray tends to go straight to rear tyre at lower speeds and goes under the car as speed increases. Almost the same for R31, but later on (and only R31 displays this knick in spray flow as seen on my pictures). Sort of virtual skirt in the rear half of the floor, when you want - more precise description will be flow lines bending in outside direction. Conservation of momentum, nothing to argue.

Adds to downforce at the rear and could decrease drag by "pushing" dirty turbulent flow outside, against diffuser's "sucking" force, just to the face of rear tyre.

3. Very different situation on breaking. Overrun used sparsely (they have to balance possible gains and added fuel weight), but when used, due to much quicker and hotter exhaust almost all goes out of the floor, in very slow corners even behind rear tyre. Should be very effective at speeds at which other area doesn't work so well, but they have to carry extra fuel to drive it.

Dude you are blatantly copying what i said and demonstrated ages ago!!
And you techno babbled it up.

I really need to get a blog or website.
Pearls to the swine.

[ringo]

This is the virtual skirt theory,but, SLC, in this forum,according to scarbs, is an aero guy who works in industry and he says otherwise.

He says huh.... And you carve it into your brain as absolute truth without even thinking twice about it?

hearsay vs science:
[youtube]http://www.youtube.com/watch?v=UfC4u5GCy3I&NR=1[/youtube]

Men lie, women lie, numbers don't.

Take the r31 video and go back to them and ask them why the car is breaking the laws of inside scoop F1 physics.

If Willem Toet, a more esteemed engineer than anyone on this site, would not comment on the R31. No one else should say anything about it and not be criticized.

The man simply didn't investigate it, so it was wise for him to be reserved about it. That is how complicated aero is.

I investigated it, but the investigation itself was not scrutinized by anyone. It was just met with: "this one said that, this one does this so his word is the word of the lord so you must be wrong at any cost!!".

I got to give Marekk props though, at least he tries to counter the theories on his own thinking.

[hardingfv32]

Is the goal to limit the air flow into the area under the side pods, front and side?

Would the exhaust flowing perpendicular to the air flow help seal the entrance of the area below the side pod?

Brian

[Formula None]

Video shows everything

The car is stationary in TURU's video.

Pearls to the swine.

Ironically, you're the only person I see in this thread consistently wallowing in their own excrement.

[ringo]

You can't change the facts.

Saying the car is stationary ... It's just irrational.

Ironically, you're the only person I see in this thread consistently wallowing in their own excrement.

Better than wallowing my face in egg.

[strad]

I'm of the opinion that the exhaust gases help seal the edges of the sidepods.

[shelly]

Turu movie it is interesting but:
-speed is very low (0-120kph maybe)
-we are seeing where water is going, not where gases are going. Inertia of water droplets plays a role.

I think that exhausts follow a cuved path: they help seling the lateral part of the front floor, enhancing front suction peak, and they are sucked inside by the difuser kink suction. The higher the car velocity, the more they will be deflected to the inside because of momentum of flow around the car and increased suction at the kink line.

[marekk]

You can't change the facts.

Thats right, ringo.

And the facts are:



When stationary, exhaust blows out of sidepods (which is obvious, no CFD needed).
BTW it's blowing far more to the rear (my approx 60 degree) and to the ground then anticipated in your CFD models. Exhaust jet seems to be quite wide.



Just after few meters (40-50 kph?, but obviously lower revs) spray is almost parallel to car's axis.



At +200kph hardly any deflection of water spray along the floor visible, so my thinking is almost all exhaust goes under the floor and leaves somewhere between rear wheels. At least part of it reaches diffuser IMO, but shelly's right - we still didn't see exhaust gases and we will not know for sure until we see some real smoke out of exhaust pipes.


Overrun (retired ignition) mode:
My understanding is they use pulses of fuel injections (every 50-100 crankshaft rotations or so) to drive the exhaust when breaking. Obviously those pulses of gases are very quick and hot, so they reach far out of the car, but the rest of exhaust flow is at much slower rate.

I've watched FP1 in Istanbul closely once more and overrun firing frequency is clearly higher in slow corners, but it doesn't look like static engine mapping - i'm wondering if they are allowed to use first 2-3 cm of throttle to let driver influence overrun rate ? Or maybe brake pedal use switches throttle control mode from regular to overrun ?

[Formula None]

Saying the car is stationary ... It's just irrational.

The exhaust plume shape will not be the same at 300kph and 0kph. It's irrational to expect otherwise.