Formula 1 Aerodynamics - article series and general discussion

[PhillipM]

As an aside, you might want to check the direction you've drawn for the air going through the louvres in your Rembrandt painting.

Completely the wrong way around as usual, to nobody heres surprise.

[godlameroso]

I'm correct, you don't have to apologize. The end plate and the upward curved wing slow down air, it is convergent flow. Pressure goes from high to low, if the underside of the wing is lower pressure than the opposite side, the high pressure air will flow towards the low, up and over the endplate.

Again you only look at one part of the car and not the whole thing. The air that travels under the wing and over the diffuser affects both the wing and the diffuser, and if you only focus on the wing, and not how it interacts with the diffuser you will not understand what I'm talking about.

The pulleys were meant to convey that, but I guess it was not clear. I shall try again.

Let us understand WHY the diffuser creates low pressure under the car, because this understanding is at play everywhere in the car.

Why does the diffuser create "suction"? The diffuser slows down air to ambient, and ambient air is high pressure air, so how does high pressure create low pressure suction?

The purpose is in the shape, the shape is to fan outward, now let's use our thinking caps and think, why does spreading out create low pressure?

[godlameroso]

Why would pushing air outwards create low pressure? Because if you spread out air there's less of it in any given space. If I throw a handful of water outwards, that water spreads outward, air behaves the same way, because it's a fluid. If you diffuse the fluid it spreads out, the air molecules spread out, there are less in a given space, this LOWERS the pressure. Air doesn't like that, so it will MOVE on its own to fill that low. The higher quantity of air you displace the harder the air works to fill the void. More mass collapsing under the weight of its own pressure. F1 should be well versed in that and feel it at a visceral level.

All that air you're expanding causes low pressure.

Think about every single surface of the car, every outside curve accelerates air and lowers its pressure(creates divergence of air molecules), every inside curve slows air down and raises it's pressure to ambient(convergence of air molecules). High collapses to low, fluid seeks equilibrium, equilibrium is still air at atmospheric pressure.

Every part of the car follows this, tires and all. The engine, everything that depends on air pressure works like this.

Bell mouth venturi ducts, turbulence and swirl is the fastest way to get cylinder filling. The turbo, everything in the car that deals with air is like this.

The front of the tire is high pressure, the rear is low pressure, high goes to low, and turbulence is the fastest way for air to mix, and the tire is spinning which is already mixing the airflow, so it is turbulent flow.

The only reason you like laminar flow and are afraid of turbulence is because your formulas suck at predicting turbulence. Turbulence follows the same laws of air, which are incredibly simple and made needlessly complicated.

I respect the tools you EARNED the hard way, I don't have the stomach or dedication for it, I learn a different way, and I completely understand and actually respect you massively for having to go through that. To willingly learn the symbols and language needed to function in that world is a hell of an accomplishment. I honestly apologize if you think I'm devaluing that in ANY way whatsoever.

[Steven]

I'm not sure why this is even an argument.

As for ground effect, maybe it's good to read this first before further building a disagreement about diffusers. If one doesn't trust people on this forum, why not check a public article by Willem Toet? https://www.racetechmag.com/2017/08/wil ... diffusers/

As for those vents in the endplates, people say your arrow direction is wrong (so they should be pointing upwards, as in: air is flowing from outside of the endplate to inside. Then, you say this:

I'm correct, you don't have to apologize. The end plate and the upward curved wing slow down air, it is convergent flow. Pressure goes from high to low, if the underside of the wing is lower pressure than the opposite side, the high pressure air will flow towards the low, up and over the endplate.

Personally, I can't really relate this comment to these slots. The slots we're talking about are positioned lower than the main wing's surface, meaning there is lower pressure in between the endplates. And by your logic, with air flowing from high pressure to low pressure, it will flow from the outside to the inside of the endplates there.
Maybe there is some misunderstanding, but I've lost the logic here.

[godlameroso]

Suddenly tornado tubes make sense. Convergence, Divergence, and Swirl.

[godlameroso]

I'm not sure why this is even an argument.

As for ground effect, maybe it's good to read this first before further building a disagreement about diffusers. If one doesn't trust people on this forum, why not check a public article by Willem Toet? https://www.racetechmag.com/2017/08/wil ... diffusers/

As for those vents in the endplates, people say your arrow direction is wrong (so they should be pointing upwards, as in: air is flowing from outside of the endplate to inside. Then, you say this:

I'm correct, you don't have to apologize. The end plate and the upward curved wing slow down air, it is convergent flow. Pressure goes from high to low, if the underside of the wing is lower pressure than the opposite side, the high pressure air will flow towards the low, up and over the endplate.

Personally, I can't really relate this comment to these slots. The slots we're talking about are positioned lower than the main wing's surface, meaning there is lower pressure in between the endplates. And by your logic, with air flowing from high pressure to low pressure, it will flow from the outside to the inside of the endplates there.
Maybe there is some misunderstanding, but I've lost the logic here.

High, above the diffuser next to the spinning tire, with the brake duct winglets and all the furniture on the lower part of the car, the air is high pressure. The center of the diffuser, and tips of the rear wing are low pressure. Those are the 3 main low pressure zones that generate the downforce in the rear end. The goal is to have static pressure over the diffuser just like James Allison said countless times.

The L in my drawing is there because it's an area of low pressure, being fed by the higher pressure underneath over the diffuser. The underside of the rear wing, and the retraction form a venturi that accelerates the air under the tips. That is why the spoon wing works so well. The vents under the wing help lower the pressure at the tips.

Red Bull, being smarter than the average F1 team understand this very well with their spoon rear wing, the vents which create more divergence under the wing, and the serrated diffuser which adds energy to the divergence caused by the diffuser flow and airflow over it. The rest is down to the adaptability of their chassis.

It's one thing to aid diffuser extraction, but it also helps to have rear wing extraction at the end plates.

By channeling air down it creates higher static pressure over the diffuser, creating greater pressure difference over and under. The vortices that are generated by the diffuser are by the air going over and around to the center of the diffuser. The low pressure is in the center at the kink where air is accelerated the most, and higher at the edges where it's slowed down. That's the drag of the diffuser.

The bargeboards and front wing work the same way.

[hollus]

The goal is to have static pressure over the diffuser just like James Allison said countless times.

Yet, teams used beam wings just over the floor’s end when rules allowed, so that is only under certain circumstances.
It is all a bit more complicated that it looks, and a large game of give and take.

[godlameroso]

The goal is to have static pressure over the diffuser just like James Allison said countless times.

Yet, teams used beam wings just over the floor’s end when rules allowed, so that is only under certain circumstances.
It is all a bit more complicated that it looks, and a large game of give and take.

Understanding evolves, I reckon if teams knew then what they know now, 2008 cars would look a heck of a lot different than they did. Vortex tube video shows everything.



The air in the bottom pushes the water up and keeps it from flowing down, it creates a lift force on the water when the air is still. But if you spin the water, "part the sea" if you will, the air flows into the top bottle, the vortex of the water creates divergent airflow which pulls the air from the bottom bottle into the top one, and water is allowed to be pulled down by gravity.

Notice the diffusion of the water by the bottom water bottle creates divergence for the water. This lowers its pressure at the center, allowing air to pass through that water divergence(low pressure zone), which itself creates its own air divergence, the air then converges at the top raising the top bottle to static/still air pressure.

[godlameroso]

You can induce centrifugal motion on a vortex to strengthen it, you don't need heat but it sure helps.(raises kinematic viscosity of air)

[jjn9128]

The goal is to have static pressure over the diffuser just like James Allison said countless times.

Yet, teams used beam wings just over the floor’s end when rules allowed, so that is only under certain circumstances.
It is all a bit more complicated that it looks, and a large game of give and take.

Beam wings work best when they are placed just behind the diffuser, to lower the base pressure of the car. It does 2 things, help with flow attachment by reducing the pressure gradient in the diffuser, and something called diffuser pumping, where the lower base pressure lowers the pressure along the whole floor. The only time I think beam wings were above the top deck of the diffuser was the 2009-13 regs because they were forced to be there.

The double deck diffuser caused lower pressure on the top deck of the lower diffuser, but the advantage of the increased expansion of the air outweighed the negatives.

[hollus]

Beam wings work best when they are placed just behind the diffuser, to lower the base pressure of the car.

So, in 2009-13 the beam wings were right above the diffuser, while before 2009 they were above and behind (whas that fully behind, or overlapping?) the diffuser.
Would I be correct to assume that the "behind" part was because it was allowed by the rules (the best place allowed by the rules), while the "above" part was because it was limited by the rules, but teams would have liked to put it even lower?
I guess what I am trying to get to here (pure speculation) is that the bast place would end up being exactly behind the diffuser and exactly flush with the diffuser height, which would essentially have built a larger diffuser?

But the point remains, high pressure right above the diffuser is trumped by the chance to achieve even lower pressure just below the diffuser, because, indeed, the benefits of that lower pressure extend somewhat all below the car's floor, making all the floor work better. Or that is my mental model anyways.

[jjn9128]

I guess what I am trying to get to here (pure speculation) is that the bast place would end up being exactly behind the diffuser and exactly flush with the diffuser height, which would essentially have built a larger diffuser?

Yeah. It depends on what's ahead, so bodywork and suspension would ruin a clean flow to the wing - if you look at cars from the 80s/90s the beam wing is quite high because the rear bodywork is so tall, whereas it's lower in the 00s partly due to regs and partly because the rear body is more streamlined.

But the point remains, high pressure right above the diffuser is trumped by the chance to achieve even lower pressure just below the diffuser, because, indeed, the benefits of that lower pressure extend somewhat all below the car's floor, making all the floor work better. Or that is my mental model anyways.

Depends on how low you can get the base pressure vs how much you lose by lowering the pressure on the top deck of the diffuser. I'd say 9 times out of 10 the lower base pressure trumps the negative for the diffuser though.

[godlameroso]

Why do the slots help the vortex formed under the rear wing? Because the slots are in line with the vortex rotation.

The offset glass in this video gives cooler denser higher pressure air outside a way to fill in the rising hot air. Because the offset is forcing the air to swirl it spins the hottest air at the center creating a fire vortex.



The slots on the endplates behind the rear wing are in line with the rotation of the vortex adding to it's "twist" strengthening the vortex.

Since I absolutely love to annoy you with my caveman paintings.

[PhillipM]

And they're still rotating the wrong way.

[godlameroso]

And they're still rotating the wrong way.

Nope, they're rotating the correct way. It isn't the other way around. It wouldn't make sense from a pressure gradient point of view. I'll be the first to admit when I'm wrong, and take it in stride, you know this. The kink of the diffuser is the fastest bit of air that's moving under the car, thus the lowest pressure.

As we know pressure goes from high to low. If the diffuser diffuses air, spreads it out, then the pressure is higher at the periphery of the diffuser than at the center. High goes to low, therefore the flow is towards the center, and up.



Towards the center and up. Look at the sparks. The Mercedes T-wing is shaped to follow the path of the airflow kicked up the the diffuser.

I'm not some high IQ guy, I got a 1080 in my SAT test, that's like barely average. I can't make my brain think in formulas, or an academic sense. However I'm not a complete tard, I kind of get what's going on, I am somewhat in touch with this process. I wouldn't talk about it if I didn't know, which is why I don't talk about electronics.