Exhaust Blown Floor - Forward Exhaust Exit

[ringo]

An F duct works by "wake control". There are some scholarly articles online on the topic. It does work by filling the low pressure area behind the wing, that is a part of it. If you going to say it decreases induced drag, then you must ask what is induced drag and what causes it? What other types of drag are there etc.
It's all under wake control.
The same is being done with the exhuast on the R31 with respect to the front wheels.

They are killing 2 birds with one stone with the exhaust. They are getting downforce, and drag reduction with the forward exit pipes.

There is more evidence in Q2 and Q3 today when the renaults cross the start/finish line. You can see the difference in the heat waves between them and the other cars.
The mirage on the track is muddled more to the front on the R31 and to the sides, where as for the other cars it's muddled from behind the rear wheels, and also wide, but not as wide as the r31.



I think the rear blown floors are also doing the drag reduction thing but for the rear tyres instead.

[triart3d]

Senior Staff don't phase me. Logic prevails; they mislead you.


Like wise this picture is confirmation of a logical analysis. Something we all saw with CFD and MS paint. Some refused to believe their eyes unfortunately.

So I think those Senior Renault guys were talking BS, and hiding what the car was really doing.

water form front tyres don't reach rear tyres, as on all other cars




Images from formula1.com

[marekk]

90kph, off throttle, overrun = big exhaust temp/speed, all goes out. No big deal, at this speed car is limited by mechanical grip anyway.




+200kph, full throttle, no visible exhaust = all goes under the car.

100% as explained before. No Senior Renault guys talking BS

[ringo]

this isn't showing anything it's too far away. And even thenthere is a hint of the side blowing ahead of the rear wheels. Where's the exhuast blowing underneath?

why don't you give up?



This is on the front straight, where the car is going way over 220kph.



This is in the corners where it matters most. ^ Clean as a whistle under the diffuser, no exhaust heat.

You can't be telling me the gas goes under the diffuser only at high speeds; which is the wrong time to blow the diffuser. Shouldn't it blow the diffuser at low speeds, speeds you can take a corner with?
How do you explain that with your theory?



At low speed it blows very widely to the sides, increasing downforce near the center of the car for good balance and center of pressure.

At high speed the skirt tucks in a little more and has the drag reduction effect. The effective floor size is slightly reduced as well but it's on the straight where DF is not so critical.

Marekk you're hanging by a thread on a non existent comment from BSing Senior Renault team members saying anything to keep their secret under wraps.

Logically, blowing the diffuser in the way you are talking is simply a waste of energy.

[hollus]

Ringo, air turbulence is a poor indicator, as the objects that you see distorted are those that are many meters beyond the hot or turbulent air.
I see the exhaust stream mostly missing the car at low speeds and mostly going under at high speeds. Logic dictates that at lower speeds it will go more open, as the free air stream is weaker. We all agreed on this.
Still no clear proof either way for me, all I see is that some exhaust air goes wide, some goes under, and the amounts change with speed.
By the way, in that pic in a low speed corner, all the air goes wide in the side of the car in the exterior of the curve, but the car turning in and a bit of centrifugal force effect would help with that, wouldn't it? In the same picture there is no indication of any exhaust driven air in the side of the car inside the corner. Clear proof that only one exhaust is blowing, for sure, and the Renault have F-exhausts!

This is like flex, everything moves, many effects are transient, and we'll have a hard time clarifying it with still pictures.
Many of you say videos from FP1 show it clearly. I'd love to see them and be convinced that the exhaust gas does not go under the floor, but I had no access to FP1. Any chance anyone could post a video or a link to a video? I searched yesterday for one, with no luck.

[Pierce89]

Ringo, air turbulence is a poor indicator, as the objects that you see distorted are those that are many meters beyond the hot or turbulent air.
I see the exhaust stream mostly missing the car at low speeds and mostly going under at high speeds. Logic dictates that at lower speeds it will go more open, as the free air stream is weaker. We all agreed on this.
Still no clear proof either way for me, all I see is that some exhaust air goes wide, some goes under, and the amounts change with speed.
By the way, in that pic in a low speed corner, all the air goes wide in the side of the car in the exterior of the curve, but the car turning in and a bit of centrifugal force effect would help with that, wouldn't it? In the same picture there is no indication of any exhaust driven air in the side of the car inside the corner. Clear proof that only one exhaust is blowing, for sure, and the Renault have F-exhausts!

This is like flex, everything moves, many effects are transient, and we'll have a hard time clarifying it with still pictures.
Many of you say videos from FP1 show it clearly. I'd love to see them and be convinced that the exhaust gas does not go under the floor, but I had no access to FP1. Any chance anyone could post a video or a link to a video? I searched yesterday for one, with no luck.

My thoughts exactly

[ringo]

There is no indication that it goes under.
None whatsoever. Worst of all the energy content of the exhuast is massively depleted by the time it would reach the diffuser. The temperature actually drops down to about 50 or 70 degrees C.
Worst of all the tyre would create turbulence for the gases as they crash into it and deflect into the diffuser. It wont be as smooth or as high in energy as the other solutions like the redbull's or even the mercedes.

There is no reason for it to go under the car at high speed, as it it counter productive. Secondly i showed clearly on the start/finish straight, and also with the use of CFD that the gases go nowhere under the diffuser. and even if a few streamlins go there, it has no benfit at all.

What is very amusing is that no one is bringing any real logic to the discussion. I wish i was more convincing, as it is clear to me thermodynamically and in terms of fluid mechanics that that the gases going under the diffuser is a pointless exercise with the exhuasts being over 1.5m away.

By the way, in that pic in a low speed corner, all the air goes wide in the side of the car in the exterior of the curve, but the car turning in and a bit of centrifugal force effect would help with that, wouldn't it? In the same picture there is no indication of any exhaust driven air in the side of the car inside the corner. Clear proof that only one exhaust is blowing, for sure, and the Renault have F-exhausts!

This is like flex, everything moves, many effects are transient, and we'll have a hard time clarifying it with still pictures.
Many of you say videos from FP1 show it clearly. I'd love to see them and be convinced that the exhaust gas does not go under the floor, but I had no access to FP1. Any chance anyone could post a video or a link to a video? I searched yesterday for one, with no luck.

No offense Hollus but what you are saying is not evidence it's technobabble.
It's just an opinion with a bunch of tecno jargon in it.

Centrifugal force in a corner would have little effect on the gases. Their mass is very low, and when compared to their energy content the mass and any force on the particles is even more negligible.
We can't actually see the exhaust, we can only see how it interacts with the imediate environment. Once side of the car could be blowing against water on the track while the other could be blowing dust and harder to see the effect. It doesn't mean it's an F ducted exhaust.

By the way, everyone is changing tune now. I never knew you accepted that it blows wide.
What happend to the strongly backed insider info from the renault bosses?

That video of the CFD showing what happens all the way up to 200mph was put up months ago, it was rejected as rubbish. When in fact it's the most accurate explanation so far.

I'll post it again:
[youtube]http://www.youtube.com/watch?v=8CtLB7g5s9s[/youtube]

The gases do not go to the diffuser. If they did (which they do not!) at 200+ mph anyway, it wouldn't be of any use.

Still waiting for the side skirt theory to be debunked. More evidence just keeps coming in to strengthen it.

[hollus]

I am not saying that you are wrong, Ringo. It starts to look even to me like you might very well be right! But there is some evidence, in the picture a few posts above, (P1, time 59:28) that under some conditions some air where the exhausts should be producing gas, indeed goes under the car. That picture is no definitive proof, it is not clear enough, the gases are not colored, but they seem to go under the car. I never claimed to have definitively proven that it happens, and I think from the beginning I said that I think that some air goes under the car. Some, more in some conditions, less in others.
I clearly haven't proven anything, but neither have you. You show quite valuable hints, but I still haven't seen an irrefutable proof, and apparently neither have others, and it is not for you to decide when we are convinced.
Turbulent gas in pictures is a valuable hint, but it can come from millions of sources, it could be 30 meters behind the car, and I swear, one couldn't possibly see it if it was under the car. CFDs are nice and valuable, but that model is not a R31, the positions and speeds of those exhaust gases are approximations, cooling from contact, radiation, etc is hell difficult to model and a 5 minutes calculation in a PC cannot possibly capture the details of what is going on. Hell, look at how difficult Virgin is finding it with years of CPU time! And even there, some times, some of the gas seems to seep back under the car's floor.
You are making a very compelling case, but please, stop telling us to be convinced already! There are no points for winning these discussions, we are here to learn (at least I am).

[marekk]

It's my pure speculation, so i could be totaly wrong of course.

We've discused already how the cooling gases under the floor add to cars downforce and i still stand by my ideas with this.

We should not forget this car is desgined and built for RK, and his strenghts are/was very late, hard breaking and good feeling for mechanical grip - so i can see benefits from high downforce (without high drag) at the end of the straights for R31/Kubica package.

Following few snapshots of Petrov's run in FP1 - just after turn 8, moer or less one second apart.

I can clearly see water spray from front right tyre disapearing under the floor as the car accelerates (first 2 stills even show some bending of flowlines due to FEE IMO):

[ringo]

I am not saying that you are wrong, Ringo. It starts to look even to me like you might very well be right! But there is some evidence, in the picture a few posts above, (P1, time 59:28) that under some conditions some air where the exhausts should be producing gas, indeed goes under the car. That picture is no definitive proof, it is not clear enough, the gases are not colored, but they seem to go under the car. I never claimed to have definitively proven that it happens, and I think from the beginning I said that I think that some air goes under the car. Some, more in some conditions, less in others.
I clearly haven't proven anything, but neither have you. You show quite valuable hints, but I still haven't seen an irrefutable proof, and apparently neither have others, and it is not for you to decide when we are convinced.
Turbulent gas in pictures is a valuable hint, but it can come from millions of sources, it could be 30 meters behind the car, and I swear, one couldn't possibly see it if it was under the car. CFDs are nice and valuable, but that model is not a R31, the positions and speeds of those exhaust gases are approximations, cooling from contact, radiation, etc is hell difficult to model and a 5 minutes calculation in a PC cannot possibly capture the details of what is going on. Hell, look at how difficult Virgin is finding it with years of CPU time! And even there, some times, some of the gas seems to seep back under the car's floor.
You are making a very compelling case, but please, stop telling us to be convinced already! There are no points for winning these discussions, we are here to learn (at least I am).

Well that can't be argued with, this may just be another flexi wing thread with no end in sight then. There simply wont be any definitive proof to lay it all out in front of everyone to see. I know we wont be getting it from renault either, as they will not reveal anything about a technology they might use next year as well.

[Speeed24]

I don't know if this has been mentioned but Steve Matchett, who works for Speed TV and who previously worked as a mechanic for Benetton (now Lotus Renault GP) and who still has contacts within the team and with other engineers in F1, said that the goal of the FEE was to create vortices on the side of the floor. When cornering this would block air from the sides from entering and slowing the velocity under the floor. It also keeps the high velocity air under the floor from escaping. I guess this supports the virtual skirt theory.

[Pierce89]

I don't know if this has been mentioned but Steve Matchett, who works for Speed TV and who previously worked as a mechanic for Benetton (now Lotus Renault GP) and who still has contacts within the team and with other engineers in F1, said that the goal of the FEE was to create vortices on the side of the floor. When cornering this would block air from the sides from entering and slowing the velocity under the floor. It also keeps the high velocity air under the floor from escaping. I guess this supports the virtual skirt theory.

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.

[Pierce89]

I don't know if this has been mentioned but Steve Matchett, who works for Speed TV and who previously worked as a mechanic for Benetton (now Lotus Renault GP) and who still has contacts within the team and with other engineers in F1, said that the goal of the FEE was to create vortices on the side of the floor. When cornering this would block air from the sides from entering and slowing the velocity under the floor. It also keeps the high velocity air under the floor from escaping. I guess this supports the virtual skirt theory.

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.
SLC Post subject: Re: Renault R31
Posted: Mon Jan 31, 2011 3:31 pm


Replies: 1289
Views: 195776

If the exhausts do indeed exit towards the front of the car the exhaust outlets will be just behind the bargeboard blowing fumes out and rearwards towards the leading edge of the floor. The additional mass flow provided here will increase the main floor suction peak as well as strengthen the T-tray/...

[ringo]

Calling names and using that as some kind of backing doesn't help the discussion.
SLC never said outright he's an experienced aerodynamicist.
He says she says hearsay only results in misinformation and a lot of back tracking.

Willem Toet is a prime example of an experienced aero guy, and he rather not say anything. Reason being, he has not seen any scientific evidence for it.
That's how we should all operate.
No one is credible here unless they presented something reasonable. Name chanting cannot suffice.

Remember the hyped blowing the starter hole theory?
Everyone jumped on that one. It only took time for it to be forgotten as any form of benefit.

[shelly]

I disagree with you ringo.
I do not think scarbs informers have put him delibarately on a wrong track, as you do.
I have read some post from SLC and they show a deep understanding of modern f1 aerodynamics; remember also that at the beginning he mocked this forum, saying that his colleagues and him used to laugh at the comments of the people in it.
I believe he has worked in f1 in the past and now is still in aero in another industry.

As far as reasonable proofs, for the moment we lack them: images do not show much.
Even if we had a professional level cfd run we still would not have conclusive evidence.