The F1 Technical Developments Thread

ahpadt

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He's done very well with 'exhausts pop out here', but he never quite manages to explain why a configuration is actually better.

Obviously if you are an engineer it will look like primary school analysis, however, if you are not and simply a regular fan then it's more information than you could ever need.

On The Flying Lap, quite a few oldtime engineers have been impressed by Scarbs' knowledge.
 

WillDAQ

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Obviously if you are an engineer it will look like primary school analysis, however, if you are not and simply a regular fan then it's more information than you could ever need.

Exactly, normally I would agree that Scarbs is very good, however in this case it's a perfect example for Cellos to show us that he knows more "than you'll ever know about the tech, engineering, and physics of these cars."

Lets all bask in the reflected glory.
 

bone

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Perfect timing then... further up in the thread you'll see i've been unsubtly hinting how the blown diffusers work. So far no one has put two and two together... perhaps you could bring your massive intellect to bear on the problem.

you mean this post?

The problem is that you have to take a step back and consider the options. The exhaust provides the potential to locally energize some flow, but what flow to energize? Just shoving it under the floor does little.

Here's a clue, what does the strake below the arrow do?





Where would it be in this diagram?


yeah, that was very informative :rolleyes:
 

Cellos88GT

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We are talking about F1 here, if you know anything then you know that they would find a way to govern the blower or the spinner to only work at a certain period of time. you know they could and thats my point.

For a supercharger, it depends on the kind, but essentially you would need two things:

1. Some kind of clutch/gearbox system on the pulley or shaft linkage to engage and disengage it that can handle the RPM and Torque loads of the engine. Also since we're talking F1 here, I imagine they would have a super charger that would make an insane amount of boost, which means the supercharger will have a lot of mechanical drag. If such a supercharger was to engage at 15K-17K RPM the engineers better make sure that components in the engine and transmission can handle the repeated actuation of this torque shock load. The torque shock can be reduced by slipping the clutch but you can only reduce it so much.

2. How are you going to feed the engine air when the supercharger is not engaged? Well, you can either do one of two things; you can either by-pass the supercharger making the engine NA or you can put a transmission system in the input shaft of the supercharger and reduce its speed so it gives a very low level of boost but can feed enough air to not starve the engine.

For Turbocharger its a little easier as you can simply have the exhaust bypass the turbo so that it doesn't spool up.

As far as KERS and DRS, well i disagree with the KERS idea you have because i just think it works better as a one area thing. with the DRS, i think its great for the sport. Im like a little kid when i see that wing flap open. it looks great and to the first time fan im sure they see the same thing.

Now, i have seen you say this on one or two occasion during this "argument". You say


Please explain this, are you an aero engineer or just a fan with lots of knowledge? im asking because you seem to know what your talking about(?). Im guessing you have a PHD in some form of engineering based on the fact that you are claiming more intelligence on the subject. I dont know you so i wont assume your being dumb here but if you have an engineering PHD and your only 23 then you are very capable of telling the people here how things work. My guess is you dont and on that point you shouldnt assume you know more. As was pointed out in the last thread, you should reread the rules. i dont mind debating with you but you need to refrain from calling people names and insulting intelligence. people from all over the world and all walks of life are in this forum and you have no knowledge of who they are or what they do. lets cut with the name calling and the assumptions. you might be very surprised and humbled to find who you are talking to. reply?

According to esppy, since he knows everything about me, I work for Fiat building plastic models of their vehicle lineup.

According to myself, I have my B.S. in Applied Physics and I did my senior thesis on the aerodynamics of race cars. I currently work as an engineer for Case-New Holland under Fiat Industrial. I plan on getting my Masters in Aero and Mech-E but I wanted to work for awhile before I went back to school and I have to save up some money too.
 

Cellos88GT

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Perfect timing then... further up in the thread you'll see i've been unsubtly hinting how the blown diffusers work. So far no one has put two and two together... perhaps you could bring your massive intellect to bear on the problem.

My understanding is that due to the high turbulence where the diffuser is, the exhaust aids in providing flow over the diffuser reducing this turbulence and in turn "energizes" the flow of the low pressure air that exists in that region.
 
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WillDAQ

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My understanding is that due to the high turbulence where the diffuser is, the exhaust aids providing flow over the diffuser reducing this turbulence and in turn "energizes" the flow of the low pressure air that exists in that region.

Errr... sort of generically, but not really.

Ok so lets start with the strake as shown here:



That's at an angle to the onset flow (which is coming in from the sides of the car) and hence a vortex is formed along the top of the strake, you can even see a little kick at the end of the strake just to help it along.

This vortex runs off the end of the strake and straight over the exhaust. The high energy exhaust flow gets entrained into the vortex, strengthening it further. This vortex heads back towards the rear of the car.

Now the rear view:



Here we have the magic 5cm gap, the reason it's so important is that you can shove your vortex straight down it, missing the diffuser entirely. So we missed the target? Well no, because you have to consider the rest of the flow field.

The rear wheels create huge areas of unstable separated flow, normally this flow impinges on the rear of the diffuser destabilising the flow inside the diffuser. Unstable flow separates more easily, limiting how much downforce you can generate.

But now we've created a barrier, the high energy vortex is stable, predictable and placed directly between the diffuser and the wheel flows, stabilising the flow inside the diffuser and allowing more downforce to be generated.

So in conclusion the blown diffuser doesn't blow the diffuser, it blows the wheels instead.
 

Cellos88GT

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Makes sense, so instead of a wild vortex/turbulent flow, you have one that is controlled and directed (strake + exhaust) so that you can manage the amount of air going to the diffuser and thus design a diffuser that can maximize this "controlled" flow. I should have elaborated in my response by saying that the exhaust doesn't blow over the diffuser, it just merely assists the air going over it by directing the air that goes around the wheels. The older designs (80s) blew exhaust directly over the diffuser which worked but it made the rear a bit skittish during on/off throttle conditions.
 
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WillDAQ

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I should have elaborated in my response by saying that the exhaust doesn't blow over the diffuser, it just merely assists the air going over it by directing the air that goes around the wheels.

Well the full answer is that it sort of does and doesn't. The vortex rotates such that it will create a desirable pressure differential on the outer edges of the diffuser (think of it rotating down onto the top surface) but the effect is small as there's plenty of air hitting the rest of the top surface anyway.
 

otispunkmeyer

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If any of you have an iDevice ... Have a look at an app called wind tunnel. It is essentially a mini 2d Real time CFD app. It only allows flow from left to right but you can draw any shapes you want in the window with your finger. It's not totally accurate of course but for what it is, its at least a good approximation. Doesnt do super sonic flow, but you can do useful stuff like wings, diffusers ( kind of, in the sense of a steam turbine diffuser, but at there is no moving ground plane yet you can't quite emulate an F1 diffuser)

I just had a little go at modelling that strake ( you have to do a cross section) and you can see the vortices and you can then imagine them becoming entrained in the high speed exhaust flow. I mean it's not sup rising really given i already understand how air reacts to leaving a bluff object or surface that abruptly ends. But it's just nice to see it actually doing it and all without spending a long time faffing with fluent or similar.
 
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mpicco

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If any of you have an iDevice ... Have a look at an app called wind tunnel. It is essentially a mini 2d Real time CFD app. It only allows flow from left to right but you can draw any shapes you want in the window with your finger. It's not totally accurate of course but for what it is, its at least a good approximation. Doesnt do super sonic flow, but you can do useful stuff like wings, diffusers ( kind of, in the sense of a steam turbine diffuser, but at there is no moving ground plane yet you can't quite emulate an F1 diffuser)
.

Seeing how it took a couple of hours to simulate a simple shape using accurate CFD in my computer which is a bit better than an iDevice, I wouldn't take that app seriously at all if it does it in real time.
 

otispunkmeyer

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Seeing how it took a couple of hours to simulate a simple shape using accurate CFD in my computer which is a bit better than an iDevice, I wouldn't take that app seriously at all if it does it in real time.

It shouldn't take you a couple of hours to do a 2D shape in CFD. Even in fluent you can do simple, non-Compressible, homogenous flow over a step or similar in less than an hour using it's own grid utility.

Like I said this app doesn't claim to be accurate it is merely an approximation. Plus the grid size is tiny, like 120x160 that's why it's fast. It's not enough for a proper simulation but I guess it's good enough for a simple approximation. Good enough to give you a good idea. I've studied thermofluids, I've studied CFD in theory and used it in practice, it does behave as expected for a lot of things. I have 2 friends who do CFD for a living and they both say it provides a decent approximation for a lot of simple things ( bluff objects, wings, river meanders, baffles, steam glands....not sure about a classic orifice plate or converging diverging nozzle because they use supersonic flow which I'm pretty sure this won't model)
 

mpicco

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That's interesting... any version for non i-things?
The only small-big problem is that being accurate for simple things means... it's no use for recreating F1 where nothing is ever simple :p
 

WillDAQ

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If any of you have an iDevice ... Have a look at an app called wind tunnel. It is essentially a mini 2d Real time CFD app.

I looked at creating an app like that a while back, sadly even with the GPU you can't run something of sufficient fidelity to be accurate.

Shan't bore with technical details, but Wind Tunnel is somewhat oversimplified.
 

DubyaStep

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According to myself, I have my B.S. in Applied Physics and I did my senior thesis on the aerodynamics of race cars. I currently work as an engineer for Case-New Holland under Fiat Industrial. I plan on getting my Masters in Aero and Mech-E but I wanted to work for awhile before I went back to school and I have to save up some money too.

and my point would be a thesis is not enough for you to claim you are superior to anyone in this forum. i have a feeling that when you stop claiming that then you will be respected more. thats the issue. as i said before, you dont know who is in this forum, all you have is some avatars and a few nick names. just dont go around assuming that you know more is my point. when you have your PHD your free to talk all the shit you want.

i have a family member who has a doctorate in fluid dynamics (thats aero by the way) so next time we talk ill ask him if he can explain it. we had talked briefly before the season about it. ill post what he has to say
 

Cellos88GT

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and my point would be a thesis is not enough for you to claim you are superior to anyone in this forum. i have a feeling that when you stop claiming that then you will be respected more.

and I don't think the member who I directed the comment to had any room to claim that I am a "fake" F1 Fan. He wanted to bring the argument to that level and I provided evidence suggesting otherwise. Many of you are blowing what I said out of proportion but thats the internet so I can't say I'm surprised.

The thesis was merely to point out that I do have SOME knowledge on the subject, not to claim superiority. Sheeeeeiit, I built my own wing that I tested in the wind-tunnel at school, it's not like I wrote some extended research paper over the course of a weekend...
 
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