F1 Exhaust System

[PlatinumZealot]

I disagree as well. There are so many correction factors you can take from real world data to put into your mathematical model. You can even create a new mathematical model from real world data. Most models in fluids are like this.

[marekk]

[Mathematical models don't use anything but governing equations that you can program in. They require no 'data' to build.

Just like a suspension system can be modelled by a mass-spring-damper system. It doesn't matter what suspension type you are using they all obey the same laws of physics.

This is exactly the same for air flow.

Yes and no.
We can build a mathematical model based on basic equations (lets start with coulomb's and shroedinger's) and do very precise calculations of the system state in time.
But there's a problem: our computers are not yet up to this chalenge.
As an example (i do computing clusters for living): on 40 Tflop/s cluster (almost exactly the power of clusters used by F1 teams) we do simulation how 1 molecule of water is going through one of living cells protein (few hundreds atoms) in time frame of 100 ps. After 1 week of calculations we are halfways.
Far away from calculating F1 front wing in motion

[shelly]

I think we are not that far.

Coupled structure and flow calculations are a well explored numerical engineering subject, which goes under the name of computational aeroelasticity or computation fluid-structure interaction.

Special methods have been developed since the 50s for airplanes, and have evolved since then; studies on this subject are also relevant to civil engineering, medicine, aeolic generators, so it is an active topic of research.
It is also a standard industrial practice; most f1 standard cfd codes (fluent, starccm) include f.s.i among their capabilities.

For sure a lot of studies on fluid structure interaction are carried out within formula 1 teams, but I think the most part of the development work is done with fixed geometry.

So we are still not completely there, but we are not that far in my opinion.

[marekk]

I think we are not that far.

Coupled structure and flow calculations are a well explored numerical engineering subject, which goes under the name of computational aeroelasticity or computation fluid-structure interaction.

Special methods have been developed since the 50s for airplanes, and have evolved since then; studies on this subject are also relevant to civil engineering, medicine, aeolic generators, so it is an active topic of research.
It is also a standard industrial practice; most f1 standard cfd codes (fluent, starccm) include f.s.i among their capabilities.

For sure a lot of studies on fluid structure interaction are carried out within formula 1 teams, but I think the most part of the development work is done with fixed geometry.

So we are still not completely there, but we are not that far in my opinion.

I meant far away from calculating F1 front wing in motion just using basic matehmatical equations of physics as suggested by Sayshina.
Agree on engineering models - almost all things around us build in recent years are designed using numerical models (even cars and planes) - but these models do need some additional numbers (quite a few if you design new airliner )

[shelly]

@marekk: yes, you still need a lot of magic numbers!

[Jersey Tom]

In terms of computational speed, parametric models are pretty clutch.

Even Hooke's law is kind of a parametric model. F = -kx. You could do a FEM of your spring and come up with a force vs displacement curve for the damn thing... or just measure it and come up with your 'K' parameter.

Likewise with aero maps. If you REALLY wanted I'm sure you could include a CFD analysis in your lap simulation. Or, you measure a pretty good idea of how it works in the wind tunnel, fit a response surface to it, and off you go!

[xxChrisxx]

Mathematical models don't use anything but governing equations that you can program in. They require no 'data' to build.

Just like a suspension system can be modelled by a mass-spring-damper system. It doesn't matter what suspension type you are using they all obey the same laws of physics.

This is exactly the same for air flow.

This quote is acually something I said about a year ago.
However it seems to be taken out of context.


It was originally an explination to autogyro who thought that using a computer to simulate things were simply accumulated knowledge in a huge database. He had a lack of understanding about how CFD (cfd spcifically but simulation in general) works which was why I used an oversimplified description.

I was showing that it's possible to build computer models that require only basic equations and assumptiona. You don't acutally need any real data colleted from the past. In another thread we discussed how real world data helps us build better models.

IIrc it was an aero thread regarding CFD and wind tunnel testing. He said that we should have accumulated enough data on past wings to know what works. That thread we went into more detail about how each model requires real world inputs and fine turning. Basically why CFD simulation were validated against wind tunnel tests.

[ringo]

It can be imagined the benefits of being able to reduce the size of the headers or move them elsewhere.

These seem to be hydro formed.

[riff_raff]

ringo,

One reason that headers may seem to be so large now is a bit deceptive. It's not so much that the headers are getting larger, but that the engines themselves are getting smaller. A modern 2.4L V8 F1 engine is incredibly small and compact. But the header tube cross sections have remained fairly large due to flow requirements. And unless the laws of physics change, the primary tube length will be a function of what engine speed gives the best results.

One interesting thing about that picture though. Those header primaries appear to have two steps (diameter changes). I've seen primaries with one step, but never two. The steps are reversion points, and the ones closer to the exhaust valves are usually tuned for higher orders. The first order reversion occurs at the collector. The orders above secondary aren't usually energetic enough to be worth tuning for. But I guess every little bit helps nowadays.

riff_raff

[PlatinumZealot]

I've observed the collector, but that step thing is new to me. Almost like blowing a flute inside a flute inside another flute?

...

Very interesting

[Sayshina]

I think we are not that far.

Coupled structure and flow calculations are a well explored numerical engineering subject, which goes under the name of computational aeroelasticity or computation fluid-structure interaction.

Special methods have been developed since the 50s for airplanes, and have evolved since then; studies on this subject are also relevant to civil engineering, medicine, aeolic generators, so it is an active topic of research.
It is also a standard industrial practice; most f1 standard cfd codes (fluent, starccm) include f.s.i among their capabilities.

For sure a lot of studies on fluid structure interaction are carried out within formula 1 teams, but I think the most part of the development work is done with fixed geometry.

So we are still not completely there, but we are not that far in my opinion.

I meant far away from calculating F1 front wing in motion just using basic matehmatical equations of physics as suggested by Sayshina.
Agree on engineering models - almost all things around us build in recent years are designed using numerical models (even cars and planes) - but these models do need some additional numbers (quite a few if you design new airliner )

I've quoted the entire post this time because last time there seems to have been an internet accident. I neither made nor agree with the quote that has been attributed to me, I was attempting to quote it in order to disagree with it.

[Darren Parkinson]

Hope this helps in regards to all topics in this thread.

http://www.epi-eng.com/piston_engine_te ... nology.htm

[hardingfv32]

I question the reversion theory. I think the steps could be an effort to form a tapered exhaust primary to maintain exhaust gas flow as the gas temps change/cool. You would need to start with a fully tapered primary tube before bending. Porsche once did this, but the configuration of their system was very simple. To do a current F1 system would require very special tooling. Possibly molds for each primary tube that could then be used for hydro forming.

IF the F1 teams thought that such a project beneficial. they would have done it years ago when they had the budget. Current systems are all hand fabricated by the teams or their subcontractors from preformed bends.

Question: You can observe from the above photo that the first step is NOT located at the same distance from the exhaust flange for each of the primaries. Why would this be? No physical packaging reason for this. I personally own a couple of F1 exhaust systems for the V10 Renault time period. One system is stepped and the steps are also NOT equally spaced.

My second Renault exhaust system is from the previous season (one year older) but it is not stepped. Seems odd to me the Renault would just have discovered the benefits of a stepped system. From my own dyno work with stepped primaries, I can not see the benefit. I can detect a 5% change in primary length, but nothing for the use of steps in the primary. Certainly not a mod that pops out on the dyno.

Brian

[PlatinumZealot]

I've observed the collector, but that step thing is new to me. Almost like blowing a flute inside a flute inside another flute?

...

Very interesting

Hey max, why did you remove my Xhibit picture? Xhibit is a highly respected figure in the automotive circles. He is usually associated with things that are inside of things.

[MIKEY_!]

Are variable pressure exhausts allowed? Say having a spring butterfly valve in the pipe somewhere.
Does that fall under variable geometry exhaust (Tech article 5.7.2)?