Exhaust Blown Floor - Forward Exhaust Exit

[ringo]

I agree with Pierce. Allison seems to suggest that the exhausts follow a path even narrower than waht I expected, getting trapped into the vortex system of the barge boards

It's not narrower than expected. It's just as expected. It doesn't get trapped in any vortex system. That section at the front is what creates the vortex.

I'ts all based on the wing section, and clearly is difficult to get right.

this was a failed attempt months ago, but it had the right idea. gas speed was too low and the pipe was blowing half way on top the flow and half bellow.



Even then it was not going under the diffuser much, only the top flow was going towards the center.






The flow was too close to the body. This is 38m/s of air speed. With 220m/s it would be much effective., sadly i changed this wing section to one less effective at creating a vortex. Anyway it's not something one person can fine tune.

The angle of flow is not constant, it changes with the speed of the car. You need the pipe to be 90 at low speed so at a certain speed it hits the section just right.
You change the pipe angle according to what speed you want it to be optimum.
You also need many other factors correct to get the best out of it. No easy task, but....

Agree now that it has nothing to do with the diffuser?

So shelly what's the verdict on the "amature" cfd. back when it was political suicide to go up against the big shot inside scoopers?

[ringo]

Would this "blown wing" be better for car balance being during different exhaust flow levels, being that it is located close to the center of the chassis?

Brian

from renault thread:

So Renault seem much more concerned with the impact that the FEE has on the leading edge of the floor and it's suction peak than the course of the airflow towards the diffuser or not.

Also an indicator that the exhaust gas velocity is around 1000mph.

I personally believe this article discredits the people who said the Renault exhaust gas wasn't going under the floor.

On the contrary. The floor exist all over.
It discredits the diffuser people.
The exhuast comes into contack with the front parts of the floor and flow coming from the splitter.
That is the only place where the speeds are 6 times the speed of the car.
At the diffuser the speed is greatly reduced.
So this reinforces everything that was said in the front exhuast thread.

On average, in the corners, the speed of the exhaust gasses is around 6 times the speed of the car. If this high speed gas can be directed at the underside of the floor, then as far as the part of the floor that is in contact with the exhaust is concerned, it will produce downforce just as if it was going 6 times as fast. The extra downforce that is produced is substantial and can improve the laptime of the car by around 1sec/lap. “

These speeds only exist at the pipe exit, no where else, as the gases lose energy as they move down along the car. So in contact must mean in front of the car.



parts in contact with the exhuast? Here they are.
6 times the speed of the car would make this simple and stubby airfoil shaped edge of the floor behave like it was 36 times bigger in area.

Also the speed calculation that i was touting all allong and no one believed it.
220m/s was my conservative estimate and it's basic thermodynamics.
Divide that by 6, 36.6m/s or 131 kph. hmm seems close enough for a low speedturn.
Let's take it to the FEE thread, cause this is very relevant to that thread.

The balance would be very centralized. Imagine the car with big wings in the center of it. Jenson Button would love a car like this, as he wouldn't need to be fiddling with the front wing much.

[Pierce89]

Where do you get your theory from? which reference?

The exhuast speed is 220m/s it's not 38m/s. Usain Bolt can run over 30m/s.


As to the flow, no human being can simply suggest where it's going. You need years of experience, and even then Willem Toet the aerodynamicist declined to make a guess.



but it's a good thing you bring up this picture.
If the air is going down 90 degrees, then why is there a gurney at the edge of the floor?

We always see these gurney on down-force generating devices and especially when exhaust flow is involved.

Why put the gurney if the gases never get there?

etc. etc. It's all there pierce.

please bro. At one point you claimed it was to alleviate the front wheel wake and you also said it didn't go under the floor. Also in the picture above, the part you claim is a gurney for the exhaust, Ferrari has that raised edge in that area of the floor but no FEE. I'm not trying to insult you, I just believe you're blowing your own horn when the thing's you've written prior only partially line up with what James Allison said.

[ringo]

There is more than one thing going on. Simple.
James Allison doesn't have to say more than is required.

The exhaust doesn't go back under the floor. That was clear from the beginning, images are the proof.
I haven't reneged on anything.


It's best to shift the discussion as to why renualt are still using the FEE.
We know how it works now so we can move on. Egg isn't in my face as some said months ago. It was fun, now onto figuring out the actual numbers and how those 3 benefits; the drag reduction, the central downforce, floor interaction edge out the EBD for the r31.

[Pierce89]

There is more than one thing going on. Simple.
James Allison doesn't have to say more than is required.

The exhaust doesn't go back under the floor. That was clear from the beginning, images are the proof.
I haven't reneged on anything.


It's best to shift the discussion as to why renualt are still using the FEE.
We know how it works now so we can move on. Egg isn't in my face as some said months ago. It was fun, now onto figuring out the actual numbers and how those 3 benefits; the drag reduction, the central downforce, floor interaction edge out the EBD for the r31.

I'm not saying you're totally wrong, i'm only saying you only partially right. I never said the exhaust had to go back in under the diffuser. I'm saying the point of the FEE is to create a low pressure zone UNDER THE FRONT SECTION OF THE FLOOR. That means the xhaust is sending a very intense vortex under the floor(th front section of the floor is still the floor). I also don't believe the front wheel wake drag would be much reduced. Lastly, if the xhaust goes out as far as implied in this thread then it can't really be used to seal the floor edges either. Bottom line is it reduces pressure under the front of the floor and that's what it does.

As far as why they're still using it they said the experimental rear exhaust had a Df gain in testing it just wasn't race ready.But it seems as though it creates DF closer to center of pressure it should effect balance less when producing different amounts of exhaust.

[ringo]

I'm not saying you're totally wrong, i'm only saying you only partially right. I never said the exhaust had to go back in under the diffuser. I'm saying the point of the FEE is to create a low pressure zone UNDER THE FRONT SECTION OF THE FLOOR.

partially right.

Dude youre saying nothing new hear. Read the whole thread man.
What you have in bold is the whole foundation of my discussion.

There are many things happening at the front of R31.

The theory is bullet proof. It's been simulated successfully and proven. I don't know how partially right comes into this.

Well on to the next F1 mystery.
As i don't see much of the diffuser theory guys saying anything again. No "ex" Renault "engineers" either. Imagine you guys almost fell for that one.

[shelly]

I agree with pierce 89. Imo, Allison is saying that the exhuast are always under the floor, i.e. have a narrower trajectory thatn what I expected, an a much narrower trajectory than the one ringo expected.

@ringo: why do you take allison interview as a confirmation of what you are saying?

[hardingfv32]

Saying that the exhaust flow is always under the floor is a broad statement. Does it go under the complete length and width of the floor or just one corner at the front?

Allison said that the low pressure zone of a vortex was the goal. This would seem to be accomplished by flowing across and under the front outer corner of the floor.

Brian

[strad]

I still think the gasses create a pseudo ground effects by sealing the edges of the sidepod to keep outside air out and improve the efficiency of the diffuser.
The drawings presented show that..imo.

[Pierce89]

I'm not saying you're totally wrong, i'm only saying you only partially right. I never said the exhaust had to go back in under the diffuser. I'm saying the point of the FEE is to create a low pressure zone UNDER THE FRONT SECTION OF THE FLOOR.

partially right.

Dude youre saying nothing new hear. Read the whole thread man.
What you have in bold is the whole foundation of my discussion.

There are many things happening at the front of R31.

The theory is bullet proof. It's been simulated successfully and proven. I don't know how partially right comes into this.

Well on to the next F1 mystery.
As i don't see much of the diffuser theory guys saying anything again. No "ex" Renault "engineers" either. Imagine you guys almost fell for that one.

who's the ex-Renault engineer? If you mean SLC I was under the impression he supposedly worked around F1 on a contract basis

[Pierce89]

Saying that the exhaust flow is always under the floor is a broad statement. Does it go under the complete length and width of the floor or just one corner at the front?

Allison said that the low pressure zone of a vortex was the goal. This would seem to be accomplished by flowing across and under the front outer corner of the floor.

Brian

I didn't mean the exhaust necessarily traveled the full length of the floor. i just don't think it went way out to the sides like people claimed on here.

[ringo]

I agree with pierce 89. Imo, Allison is saying that the exhuast are always under the floor, i.e. have a narrower trajectory thatn what I expected, an a much narrower trajectory than the one ringo expected.

@ringo: why do you take allison interview as a confirmation of what you are saying?

No you are misunderstanding what allison is saying. Stop putting words in the guy's mouth. They cannot go under the floor. The blowing wont work that way you see.

This is starting to look like playing devil's advocate to me. The man clearly states that it has nothing to do with the diffuser, yet you are trying to salvage something from that theory, while at the same time trying to twist the truth.

You guys are jumping from one thing to the other while i'm sticking to my guns.

The trajectory has to be wide. It wont work otherwise. Just look on the CFD please, it cleary shows what is happening both with the edges of the horns on the floor and the splitter. It can't get any clearer.
I'm starting to get tired of repeating the same thing, as it seems this is just to try to prove me wrong than any thing else.

[ringo]

Saying that the exhaust flow is always under the floor is a broad statement. Does it go under the complete length and width of the floor or just one corner at the front?

Allison said that the low pressure zone of a vortex was the goal. This would seem to be accomplished by flowing across and under the front outer corner of the floor.

Brian

I didn't mean the exhaust necessarily traveled the full length of the floor. i just don't think it went way out to the sides like people claimed on here.

Well it varies with speed. It blows wide at low speeds obviously. And those snap shots from valencia are proof.

[ringo]

I'm not saying you're totally wrong, i'm only saying you only partially right. I never said the exhaust had to go back in under the diffuser. I'm saying the point of the FEE is to create a low pressure zone UNDER THE FRONT SECTION OF THE FLOOR.

partially right.

Dude youre saying nothing new hear. Read the whole thread man.
What you have in bold is the whole foundation of my discussion.

There are many things happening at the front of R31.

The theory is bullet proof. It's been simulated successfully and proven. I don't know how partially right comes into this.

Well on to the next F1 mystery.
As i don't see much of the diffuser theory guys saying anything again. No "ex" Renault "engineers" either. Imagine you guys almost fell for that one.

who's the ex-Renault engineer? If you mean SLC I was under the impression he supposedly worked around F1 on a contract basis

Not SLC. I don't know, but scarbs got his insights from them, whoever they are.

[Fil]

Beyond the incessant circlework happening here, the most interesting thing that Allison said on TFL, was that Renault chose the path of the FEE while still on Bridgestones. And at that point, the FEE was head & shoulders above the potential of the EBD variants they were testing.

But on Pirellis, which he claims need a more rearward centre of balance (compared to Bridgestones), the (rearward) balance shift that the EBD inherently provides, at the time this is most needed, is potentially more favourable a setup than a balanced FEE.

So it sounds like they have been somewhat caught out by the change in tyre characteristics, hence them going back to the 2010 drawing board and now re-trying the EBD.