2012 Exhaust Blowing & Coanda

[Ferraripilot]

Smikle, I still don't understand how this attempted diffuser sealing blowing is superior than a system which maintains tightly draped sidepods with an integrated solution blowing between the beam wing and diffuser similar to what W03 is running. It seems W03 maintains laminar flow yet has some benefit from the exhaust as well while the RB and Mcl have ruined much of their coke bottle flow in favor of attempting to seal the diffuser. Am I missing something as this seems to be a sloppy solution to this year's regulations?

[hardingfv32]

That looks a lot like it's making the assumption that the air around it isn't moving at all – that'll be why you're losing all your air speed

I have asked for a clarification on that detail. It has been stated in reference to his other illustrations that the body flow is present but off screen. I agree it looks odd.

This is the first and the only simulation we have of what happens to the exhaust flow as it leaves the tip of the pipe. After a lot of research I have found nothing in the public domain.

I would say the exhaust flow is additive with the body flow. Based on this simulation, it is not adding much.

Brian

[Adrian Newby]

That looks a lot like it's making the assumption that the air around it isn't moving at all – that'll be why you're losing all your air speed

I have asked for a clarification on that detail. It has been stated in reference to his other illustrations that the body flow is present but off screen. I agree it looks odd.

This is the first and the only simulation we have of what happens to the exhaust flow as it leaves the tip of the pipe. After a lot of research I have found nothing in the public domain.

I would say the exhaust flow is additive with the body flow. Based on this simulation, it is not adding much.

Brian

I mentioned in a previous post that we can compare this year's rake to last year's rake (in race trim), and that should give us a rough estimate of the amount of downforce/sealing Red Bull were able to claw back.

[beelsebob]

That looks a lot like it's making the assumption that the air around it isn't moving at all – that'll be why you're losing all your air speed

I have asked for a clarification on that detail. It has been stated in reference to his other illustrations that the body flow is present but off screen. I agree it looks odd.

This is the first and the only simulation we have of what happens to the exhaust flow as it leaves the tip of the pipe. After a lot of research I have found nothing in the public domain.

I would say the exhaust flow is additive with the body flow. Based on this simulation, it is not adding much.

I would find it extremely surprising if a 230m/s energised air flow slowed to 30m/s in the presence of a 75-100m/s air flow around it... Possibly 30m/s faster than the air flow around it, rather than 30m/s sounds realistic, but even then, if you're feeding the diffuser with 105m/s hot air rather than 75m/s air, that's a substantial gain.

[hardingfv32]

I mentioned in a previous post that we can compare this year's rake to last year's rake (in race trim), and that should give us a rough estimate of the amount of downforce/sealing Red Bull were able to claw back.

While that logic is sound, it is superseded by new and more detailed data. No way 15 m/s addition flow is going to stack up to last years 230 m/s flow.

Brian

[hardingfv32]

I would find it extremely surprising if a 230m/s energised air flow slowed to 30m/s in the presence of a 75-100m/s air flow around it... Possibly 30m/s faster than the air flow around it, rather than 30m/s sounds realistic, but even then, if you're feeding the diffuser with 105m/s hot air rather than 75m/s air, that's a substantial gain.

I do not think less dense hot air would be better. Your thought?

Brian

[beelsebob]

I would find it extremely surprising if a 230m/s energised air flow slowed to 30m/s in the presence of a 75-100m/s air flow around it... Possibly 30m/s faster than the air flow around it, rather than 30m/s sounds realistic, but even then, if you're feeding the diffuser with 105m/s hot air rather than 75m/s air, that's a substantial gain.

I do not think less dense hot air would be better. Your thought?

Why would you aim the 800° exhaust there the year before if the hot air wasn't better

[Adrian Newby]

I mentioned in a previous post that we can compare this year's rake to last year's rake (in race trim), and that should give us a rough estimate of the amount of downforce/sealing Red Bull were able to claw back.

While that logic is sound, it is superseded by new and more detailed data. No way 15 m/s addition flow is going to stack up to last years 230 m/s flow.

Brian

Of course this year's sealing won't be nearly as good as last year's. That is basically a "given" with this year's rules.

What I said wasn't "superseded" by anything. Where do you get this stuff?

And as far as I have seen, you are the only one here who believes this "15 m/s" number for the RB8.

[Gridlock]

really fast cars maintain balance while the speed changes.


Brian

You're confusing 'easy to drive' with 'fast'. Truly fast cars would be undrivable to someone who doesn't have WDC genes.

[hardingfv32]

PS I think some commenters should stick a hand in the exhaust flow of an F1 car at 18,000 rpm, would bring a bit of perspective

At what distance from the exhaust tip do you propose to make this a relevant test?

I have 1200cc, 60 hp @ 6000 RPM engine on my dyno, can I scale up the results?

Brian

[PlatinumZealot]

The only difference I see is hotter temperatures down there, and a slight increase in the flow over the diffuser. The velocity I see near the sides of the diffuser seems not to be much higher than the free air velocity so I am wondering my self if there is some other effect in play.

It could be that the cooling hence contraction of the hot exhaust gas as it travels to the rear of the car is creating a "contraction vacuum" effect near the diffuser making it easier for the underfloor gases to come out. ???

[hardingfv32]

[And as far as I have seen, you are the only one here who believes this "15 m/s" number for the RB8.

I have n smikle's simulation backing my statements and you and the others in FACT have nothing to challenge it with. I make that strong statement because I have asked on this form for such data before and been provided with nothing but ringo's Renault exhaust flows. I have also research many times on exhaust flow after the tip and have found nothing.

You have no way to challenge n smikle's simulation. That would require some data of equal standing. Opinions are not going to cut it.

Brian

[Ferraripilot]

The only difference I see is hotter temperatures down there, and a slight increase in the flow over the diffuser. The velocity I see near the sides of the diffuser seems not to be much higher than the free air velocity so I am wondering my self if there is some other effect in play.

This is precisely what I'm sratching my head about. The idea of it makes no sense to me at there just doesn't seem to be a velocity difference worth ruining all the sidepod flow over. Simply heating the air in that area doesn't really play the game either because if they wanted to simply make the diffuser more efficient, they should have aimed their path directly over the diffuser as Merc have done rather than out and down the sides with perhaps a few % more velocity than what is already present. This is a lame duck idea IMO.

[lombers]

This is precisely what I'm sratching my head about. The idea of it makes no sense to me at there just doesn't seem to be a velocity difference worth ruining all the sidepod flow over. Simply heating the air in that area doesn't really play the game either because if they wanted to simply make the diffuser more efficient, they should have aimed their path directly over the diffuser as Merc have done rather than out and down the sides with perhaps a few % more velocity than what is already present. This is a lame duck idea IMO.

I agree somewhat with this statement. I'm not 100% certain, but I think that only Ferrari and RBR have tested both such exhaust positions. If anything those teams probably have the real numbers about which solution works best, even if Ferrari's solution was just to hack away at the bodywork near the Acer ducts.

It's evident that the numbers for Ferrari didn't correlate to what they saw in simulation, so they have gone back towards a similar position to Mercedes. They do however seem to think it's worth using the outboard exhausts once they have done some re-design. It's unclear if the RBR solution is better or worse as they simply didn't have the running time with their new design, but they still probably have enough data to check this.

I am curious about whether cleaner flow over the sidepods can achieve an equal result.

[Adrian Newby]

[And as far as I have seen, you are the only one here who believes this "15 m/s" number for the RB8.

I have n smikle's simulation backing my statements and you and the others in FACT have nothing to challenge it with. I make that strong statement because I have asked on this form for such data before and been provided with nothing but ringo's Renault exhaust flows. I have also research many times on exhaust flow after the tip and have found nothing.

You have no way to challenge n smikle's simulation. That would require some data of equal standing. Opinions are not going to cut it.

Brian

You are a walking argumentative fallacy.

Just because you don't have the right answer, that doesn't mean the only "answer" you do have is right. And no one here has to "challenge" you, your numbers, or your contentions in order to be right. This is not a sport or a competition, it is a discussion.

As far as your data, you have a forum poster's simulation of a completely different car with a completely different engine and exhaust, and in the absence of any airflow, from what I have read. And, to repeat: as far as I have seen, you are the only one here who believes this "15 m/s" number for the RB8.