Formula 1 Aerodynamics - article series and general discussion

[jjn9128]

And they're still rotating the wrong way.

Centreline upwash from the rear wing and diffuser.

[jjn9128]

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.

As someone with a high level degree in aerodynamics I'm appalled at the suggestion that aero can be sort of intuited and approximated where electronics requires education

I think the problem is you're talking in terms of global airflow in regions of local airflow. So while it is true that the diffuser and rear wing vortex systems merge into a big vortex pair, at the location of the slots on the rear wing endplates they will be very much separate entities. The local flow in that region will also be from high to low pressure, so coming inboard through those slots - you see they're wing shaped and directed inwards. So while it's true that things have to be thought of holistically in terms of a whole system, there is a high degree of local variation - otherwise why bother with things like vortex generators and turning vanes?!

[godlameroso]

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.

As someone with a high level degree in aerodynamics I'm appalled at the suggestion that aero can be sort of intuited and approximated where electronics requires education

I think the problem is you're talking in terms of global airflow in regions of local airflow. So while it is true that the diffuser and rear wing vortex systems merge into a big vortex pair, at the location of the slots on the rear wing endplates they will be very much separate entities. The local flow in that region will also be from high to low pressure, so coming inboard through those slots - you see they're wing shaped and directed inwards. So while it's true that things have to be thought of holistically in terms of a whole system, there is a high degree of local variation - otherwise why bother with things like vortex generators and turning vanes?!

Birds can intuit aero, and since I have a bird brain I'm half way there

I agree that vortex generators and turning vanes work well to clean up airflow.



What do you suppose is happening, we know RBR takes the slots off to reduce drag, so how would the slots increase drag? Wouldn't the solid barrier create greater pressure differential between the wing tips and a solid barrier vs slots? If the air is coming in from the outside of the endplates as you say, giving the air a bigger obstruction would increase drag wouldn't it? If the flow is contained to within the rear wing and endplates, then the slots would help increase swirl of the vortex as I believe them to do.

[jjn9128]

What do you suppose is happening, we know RBR takes the slots off to reduce drag, so how would the slots increase drag? Wouldn't the solid barrier create greater pressure differential between the wing tips and a solid barrier vs slots? If the air is coming in from the outside of the endplates as you say, giving the air a bigger obstruction would increase drag wouldn't it? If the flow is contained to within the rear wing and endplates, then the slots would help increase swirl of the vortex as I believe them to do.

Difficult to say without looking at CFD plots to know local flow conditions. To hazard a guess though, with a higher downforce rear wing the pressure between the endplates is lower and the flow incidence higher (upwash from the wing) so bleeding that pressure off is beneficial and reduces the vorticity of that lower endplate vortex. So with a lower downforce wing they're not as effective as the flow condition is changed.

[godlameroso]

We know the air above the diffuser is static/ambient/high pressure relative to the wing. If you use the endplate retraction to extract and lower the pressure there, you're actually hindering the diffuser because you're lowering the pressure differential. If you turn the end plate retraction into a divergent venturi tunnel, and use the end plate slots to increase the swirl, you increase the strength of the vortex at the wing tip.

Now you can get away with a much skinnier rear wing, because the diffuser is much more efficient than the rear wing, and if you increase the static pressure above the diffuser, the diffuser works harder.

The static pressure is the equivalent of having someone sit on the back of the car. The higher the static pressure vs the faster the air coming off the diffuser centerline, the heavier the person. Cramming as much air as possible over the diffuser creates convergent flow, fast at the periphery slow and lethargic at the center. That gives the diffuser it's strength.

Above that the rear wing is doing its own thing, the center of the rear wing is getting turbulent obstructed airflow, the wing tips are getting nice clean airflow, the wing tips are therefore the most critical parts of the rear wing in terms of rear downforce. The rear wing tips and endplates are literally combined so if you shape the retraction to help the rear wing tips the vortex they shed will be nice and strong, even stronger if you induce swirl.

That strong swirling vortex will help extract the diffuser upwash.

Therefore that small little change of creating divergent(towards the diffuser) flow with the endplate retraction, increases the static pressure above the diffuser, and lowers the pressure under the rear wing tips.

[PhillipM]

And they're still rotating the wrong way.

Centreline upwash from the rear wing and diffuser.

Yeah but not right by the side of the endplate, there's inwash and upwash there through the slots, where they're trying to reduce the strength of the vortex off the corner of the top endplate after the upper slots got banned.

[godlameroso]

Where Red Bull was smart was, instead of cramming more airflow towards the diffuser and increase drag, they just moved the rear wing away from the retraction increasing flow divergence. The spoon shape worked out beautifully.

[Slo Poke]

Godlameroso:
What do you suppose is happening/happens with suction assisted/enhanced diffusers?

[godlameroso]

Godlameroso:
What do you suppose is happening/happens with suction assisted/enhanced diffusers?

How do you mean? The F1 diffuser is suction assisted/enhanced as is. I thought we were discussing such a diffuser.

If what you think I suppose is happening, well, imagine you have a tube full of metal rods, and you try to put another metal rod in the tube. You can't, it's full, so you have to push out a rod with a new rod. The pressure is high. You have to use a lot of pressure to shove the rod through the tube.

Now, if some kind soul starts pulling out the rods in the middle, you can just shove it right through the tube, the pressure is low at the center. You don't have to use much pressure.

The diffuser opens a void for air to pass through, it parts the sea of air, like a Formula 1 Moses.

[Slo Poke]

I’m specifically making reference to mechanical suction assist when the car is stationary. What do you suppose is happening/happens when the car is moving at racing speeds?

[godlameroso]

I’m specifically making reference to mechanical suction assist when the car is stationary. What do you suppose is happening/happens when the car is moving at racing speeds?

At racing speeds, just the diffuser, well the air that passes over is being slowed down, the slowing down is a convergent flow. Packing rods in a tube. Rods have mass, and create a downward force.

Meanwhile, the leading edge of the floor is sucking in air, those big ol' teef and flared out leading edge, ie convergent flow. High pressure leading edge flow is accelerated, then it is extracted with two turbulent counter rotating vortecies coming off the back of the car.

The diffuser then fans out the air, creating a void in the middle, which speeds up the air even faster, while simultaneously adding swirl to the two counter rotating vortices traveling under the car, which are further "swirled" by the sticky uppy bits on the edge of the floor near the Z pinch. Which shed their own vortices, but that's another topic, let's stay focused.

Because the diffuser expands in volume, it's like like the rods in the metal tube going into a wider tube, and they stick to the walls, allowing the rods to pass through the center because the pressure is lower, similar to the way the air comes off the diffuser.

After the air has been parted by the diffuser, parted like Bob Varsha's hair. The low pressure void entices all the surrounding high pressure air to flow into the low which is travelling upwards and out. The high follows because it has no choice.

[godlameroso]

Another way to think about it. If the car is still, the air is still and the pressure above and below are equal.

When the car moves, the air slows down above so the pressure increases, and the air speeds up underneath, the pressure pushing up decreases because you've accelerated the air from under the bottom. Without the air there to push up the rear of the car, it get's pushed down due to the air pressure above.

[godlameroso]

The coke bottle shape creates downforce, because the airflow through the car is convergent. The outlet airflow is rather lethargic and slow. The pressure under the engine cover is not insignificant. That mass of air is added to the overall tally of air mass pressing down on the car, as the proverbial rug is pulled out from underneath.

Lethargic slow moving air increases pressure. Imagine a crowd of folks all walking into a dead end, all those bodies close together not moving very fast, all crowded. It's going to get annoying real quick, all that pressure. You give those people an out, and vroooom, out the door stampeding each other to git out.

[J.A.W.]

Nevermind false analogy/conflation with crowdphobic anxiety 'pressure', do a fact check:

Do any F1 body aero-flows reach the transonic range, or show 'shock' or 'choke' phenomena?
Some aspects, such as vortices & buffet may correlate.

[henry]

I suspect that there is a good deal to be gained in this discussion by agreeing on some common terminology. As an example I don’t think that @JAW and @Godlameroso mean the same thing by “choke”.