Haas VF-22 Speculation Thread

[Stu]

Can someone clarify what y'all are talking about when you say the sidepod shape will push the front tire wake outboard? I don't see how this would work. The sidepods are wide, yes, but they're still lower than the top of the tires (allowing some tire wake to flow into the void left behind the sidepod) and still feature a pretty substantial undercut. To me, this would mean that the clean air wraps around the top and bottom of the sidepods, not really creating a wall of air to keep the front tire wake away.

In the photos below, I would expect the air from the centerline to wrap over and around the sidepods (blue), the adjacent air to wrap down the sidepod and move toward the floor (green), some air would go straight into the sidepod (yellow), and then the lower air would go down and around the sidepods or under the floor (orange). I don't see how air would travel around the outermost section of the sidepod to push the tire wake outboard. Further, the massive void left behind the sidepods should then bring some of the tire wake toward the rear wing. Right?

Almost!
From CFD plots that I have seen (on this forum) of how the front tyre wake behaves with the new regs the tyre wake will be drawn into the undercut area on the Haas.
If it works how I think it could/should the small ‘side-wing’ that the regs allow along the floor edge will then re-energise that flow into a vortex along the floor edge which then flows to the rear of the car exiting roughly where the rear wheel ‘deflectors’ are located.

Wouldn't the 'side-wing' only control the turbulence near the floor? Leaving the majority of the upper front tire wake to interfere with the rear wing as it's drawn toward the body? And when you say rear wheel 'deflectors', are those located on the inside of the rear tires?

Also, where can I find those CFD plots you speak of? Is it somewhere in the aerodynamic regulations thread?

The CFD plots are in the aero regs thread (they were posted a couple of weeks ago). The front wheel wake appears to be fairly well ‘down-drafted’ by the front wheel deflector, so could well end up in the vicinity of the undercut lead in. And I do mean the aero winglet appendages on the inner face of the rear wheel.
If I can link the CFD part here I will. Big thank you to @blackout for posting it originally.

[Blackout]

Thanks to theVortexCreatorY250 for that vid.

https://i.imgur.com/s0WIUwj.mp4

viewtopic.php?p=879079#p879079

[diffuser]

Are they using the sidepod upper bodywork now (not just the undercut) to create the much dreaded outwash? bad news for F1 if this becomes a trend
The sidepod intakes have been pushed forward too. Some journos said Ferrari or RB is doing the same...
The very wide sidpopd bodywork suggest completely different radiator angling and positioning too

They've (depending on who you ask) removed +20 cm from the wheelbase. That has to go somewhere, if you want to leave space behind the sidepods to keep air attatched. Moving it all forward makes sense.

[BlueCheetah66]

[adrianjordan]

Gonna be interesting seeing who the drivers get in and out of the cockpit with the side pods that far forward!!

[JPower]

Great video!

[Just_a_fan]

Gonna be interesting seeing who the drivers get in and out of the cockpit with the side pods that far forward!!

Many have been using small step ladder-type platforms in the last few years because of the huge barge board devices. I guess they'll just do the same with these cars.

[PlatinumZealot]

They want fast air over the exit of the diffuser because this makes it more efficient - the diffuser's job is to slow the air down so if you can blow fast air across the edge of the diffuser, the speed difference it has to deal with is less. The beam wing helps here too because it accelerates the air immediately below it (and thus immediately above the diffuser lip) improving the situation further. The beam wing also helps with the expansion, of course, and results in an effectively extended upper diffuser surface. That's my "school boy understanding" of it, anyway.

The air that can't go through the tunnels and goes over the floor and under the sidepod undercut, will be much higher pressure than the diffuser in general(especially if we have a choked diffuser throat). The edge wing is there to prevent or delay the air over the floor from curling under the floor. It still will curl under the floor of course because high pressure goes to low, this will create two strong counter clockwise vortices. As we discussed in the aero thread, vortices can amplify each other if they interact properly.

The airflow that is accelerated by the throat of the diffuser's massive low pressure, and the expansion fans that follow the throat, all the way to the beam wing, help drive the two vortices, and those vortices will help pull air through the floor further accelerating it. This in turn will create a bigger pressure difference between the top and bottom of the car, in a positive feedback loop similar to the way a turbo creates pressure.

With subsonic flows, or incompressible flows, diffusion slows down air, with sonic or compressible flows, diffusion accelerates air. For a diffuser to accelerate air via expansion that air already is either sonic or suffering from compression effects.

The diffuser slows the air down to meet the ambient air as smoothly as possible - that's the purpose of a diffuser on a racing car. By ensuring fast air flows over the top of the diffuser, the speed of both streams is as close as possible. This ensures that the flow behaves itself when they merge. That's why the teams design the cars with massive amounts of clear space in front of the rear floor - to ensure as good an airflow over the diffuser as possible. To prevent the very thing you say will happen - air curling under the diffuser rear lip.

The air under a Formula 1 car is not in supersonic flow.

Yes, you'll get vortices forming where air is moving laterally across the floor and meets the edge where the diffuser wall meets the floor. Those vortices will help to reduce separation in the diffuser and also mix in "unused" air from below the car which helps the diffuser too. https://www.racetechmag.com/2017/08/wil ... diffusers/

I think your theory is not fully correct. It is for other reasons why you want to prevent stagnation at the coke bottle. The main reasons is that you can use the kinetic energy of the air here to work on other surfaces. Energy is tge key word. You could have fast flowing air, but it is pinched and has lost much static pressure. You can't do much work with it.

Recovering the air speed over a diffuser actually makes less downforce if it is a bare normal diffuser. This is because the static pressure would be higher and this would cause the static pressure in the diffuser throat to be higher too. This is why you used to see teams use gurney flaps on the diffuser to lower the static pressure behind it. This adds drag though.

There would be less drag yes if the air blows over at a more recovered speed but less downforce. What you see teams do in recent times is to use the little mutli-element wings on top of the diffuser. This is to help extract air from it and keep the vortices in the diffuser more stable and at the same time not add too much drag. You can gain more from stabilizing the vortices inside the diffuser.

The coke bottle zone... The air moves almost zero speed through here. Because of the wide area and the "air dam" created by the rear tyres. The engineers extend great effort to prevent energy loss here so that the air can be used for the tyre squirt area between the diffusr and tyre, the brake ducts, the RW end plates and the little diffuser gurney elements. Also for recovery of the wake behind the rear wing.

[diffuser]

How is the first element of the front wing flat to the ground? I thought the development boxes has a distinct slope from center to the edge.

Perhaps a combination of a sweep and dihedral.

It might be a wing they never intend on using. Its just there for our amusement.
I would have expected a arch to combat the tire squirt.

[Just_a_fan]

The air that can't go through the tunnels and goes over the floor and under the sidepod undercut, will be much higher pressure than the diffuser in general(especially if we have a choked diffuser throat). The edge wing is there to prevent or delay the air over the floor from curling under the floor. It still will curl under the floor of course because high pressure goes to low, this will create two strong counter clockwise vortices. As we discussed in the aero thread, vortices can amplify each other if they interact properly.

The airflow that is accelerated by the throat of the diffuser's massive low pressure, and the expansion fans that follow the throat, all the way to the beam wing, help drive the two vortices, and those vortices will help pull air through the floor further accelerating it. This in turn will create a bigger pressure difference between the top and bottom of the car, in a positive feedback loop similar to the way a turbo creates pressure.

With subsonic flows, or incompressible flows, diffusion slows down air, with sonic or compressible flows, diffusion accelerates air. For a diffuser to accelerate air via expansion that air already is either sonic or suffering from compression effects.

The diffuser slows the air down to meet the ambient air as smoothly as possible - that's the purpose of a diffuser on a racing car. By ensuring fast air flows over the top of the diffuser, the speed of both streams is as close as possible. This ensures that the flow behaves itself when they merge. That's why the teams design the cars with massive amounts of clear space in front of the rear floor - to ensure as good an airflow over the diffuser as possible. To prevent the very thing you say will happen - air curling under the diffuser rear lip.

The air under a Formula 1 car is not in supersonic flow.

Yes, you'll get vortices forming where air is moving laterally across the floor and meets the edge where the diffuser wall meets the floor. Those vortices will help to reduce separation in the diffuser and also mix in "unused" air from below the car which helps the diffuser too. https://www.racetechmag.com/2017/08/wil ... diffusers/

I think your theory is not fully correct. It is for other reasons why you want to prevent stagnation at the coke bottle. The main reasons is that you can use the kinetic energy of the air here to work on other surfaces. Energy is tge key word. You could have fast flowing air, but it is pinched and has lost much static pressure. You can't do much work with it.

Recovering the air speed over a diffuser actually makes less downforce if it is a bare normal diffuser. This is because the static pressure would be higher and this would cause the static pressure in the diffuser throat to be higher too. This is why you used to see teams use gurney flaps on the diffuser to lower the static pressure behind it. This adds drag though.

There would be less drag yes if the air blows over at a more recovered speed but less downforce. What you see teams do in recent times is to use the little mutli-element wings on top of the diffuser. This is to help extract air from it and keep the vortices in the diffuser more stable and at the same time not add too much drag. You can gain more from stabilizing the vortices inside the diffuser.

The coke bottle zone... The air moves almost zero speed through here. Because of the wide area and the "air dam" created by the rear tyres. The engineers extend great effort to prevent energy loss here so that the air can be used for the tyre squirt area between the diffusr and tyre, the brake ducts, the RW end plates and the little diffuser gurney elements. Also for recovery of the wake behind the rear wing.

And yet the diffuser works best with fast air flowing over it. It's why the teams make so much effort to get good airflow over the diffuser. The conditions within the diffuser are helped by the strakes - that's why reducing their size last year had an effect on the downforce produced.

As for air not moving through the coke bottle region, sorry that's just plain wrong. One only has to look at flow viz / dirty cars to see the air flows through there. It's why the teams make so much effort sculpting the rear of the side pods to encourage air through there.

It's also worth remembering, of course, that the air isn't moving, the car is. The air is effectively still until the car gets to it.

[PlatinumZealot]

You said. Diffuser works best with air flowing over it. Not saying this is 100% wrong, just that it is too general. You gotta be specific. So I gave you two example to illustrate blocking on top and not blocking on top of the diffuser.

Notice that this diffuser still worked very well as intended...(Audi R18) And look at the big ole gurneys.




So it is for the entire efficiency of the package why you want to recover as energy of the air flow... It's not just for diffuser. You can crank out huge peak suction from the diffuser if you had a big ole' gurney flap on top. But obviously drag would be high. So I don't think you can make a statement like flow more air over the diffuser and it make more downforce. I dont think that is correct in all cases.

[Just_a_fan]

You said. Diffuser works best with air flowing over it. Not saying this is 100% wrong, just that it is too general. You gotta be specific. So I gave you two example to illustrate blocking on top and not blocking on top of the diffuser.

Notice that this diffuser still worked very well as intended...(Audi R18) And look at the big ole gurneys.

https://www.topgear.com/sites/default/f ... 784&h=1004


So it is for the entire efficiency of the package why you want to recover as energy of the air flow... It's not just for diffuser. You can crank out huge peak suction from the diffuser if you had a big ole' gurney flap on top. But obviously drag would be high. So I don't think you can make a statement like flow more air over the diffuser and it make more downforce. I dont think that is correct in all cases.

From memory, the rules mandated that the rear end couldn't meet the top surface of the diffuser. They were stuck with a blunt rear. The teams wouldn't have done that otherwise because it's just not as effective.

There's a reason the teams spend so much time making the rear floor clear and directing clean air across it, and that's to make the diffuser as efficient as possible.

Newey seems to have figured some of this out quite early on - look at his March 881 and you seem him trying to get over the top of the rear floor. Everyone else had bodywork that ran almost to the rear wheels and then a big fat bit of bodywork between the rear wheels. Newey used that same idea as his career developed and we see all of the team today trying to get as much airspace over the top of the diffuser - the teams even design the rear suspension to improve airflow across the top lip.

Anyway, this is hugely off topic for the this car thread.

[godlameroso]

More air over the diffuser increases mass flow, since that part creates upwash, the pressure is higher than the diffuser. More mass and more upwash = greater pressure difference between diffuser and upper surface.

Air mass = weight, more weight on top vs the bottom since the diffuser is much lower pressure. Normally air supports from all directions, when you create an imbalance by lowering the pressure under the car, the air pressure above + gravity presses down on the partial void under the car. It's like sitting on those yoga balls, while it's inflated, you're well supported etc, deflate it(ie lower its pressure) and now your bum is on the ground.

[PlatinumZealot]

More air over the diffuser increases mass flow, since that part creates upwash, the pressure is higher than the diffuser. More mass and more upwash = greater pressure difference between diffuser and upper surface.

Air mass = weight, more weight on top vs the bottom since the diffuser is much lower pressure. Normally air supports from all directions, when you create an imbalance by lowering the pressure under the car, the air pressure above + gravity presses down on the partial void under the car. It's like sitting on those yoga balls, while it's inflated, you're well supported etc, deflate it(ie lower its pressure) and now your bum is on the ground.

Flow doesn't move from low to high pressure. So you are missing out a few factors there.

I'm not bashing you guys. I just think your generalizations is not entirely correct and it's confusing new readers. So best to be specific.

I always push people towards Willem Toet's lecturers. Read this first and see what he says about relative air speed to the CL create by the diffuser (hint it's not a large effect):

https://www.racetechmag.com/2017/08/wil ... diffusers/

Then you see what I mean about using air around the diffuser to take advantage of other things like winglets. (note at the time he's refering old regs). It's not to "speed up air above the diffuser". He clearly states air speed has a secondary effect on the peak diffuser downforce.

Another little appreciated detail about motorsport diffuser performance is changing performance with speed. I won’t cover that here in detail but in the context of conventional motorsport full scale cars the impact of changing Reynolds number is relatively small. Not zero but secondary. Forces increase with speed times speed and ride height has a bigger impact than changing airflow states caused by different Reynolds numbers.

Now to make the floor/diffuser to the next stage of performance you use other aerodynamic tricks such as surrounding the floor with suction. Depending on the formula in which you race this could be by putting a wing above and slightly behind the diffuser (not legal in F1) or it could be just surrounding the it with deflectors and winglets as is the present practice in F1.

[diffuser]

And yet the diffuser works best with fast air flowing over it. It's why the teams make so much effort to get good airflow over the diffuser. The conditions within the diffuser are helped by the strakes - that's why reducing their size last year had an effect on the downforce produced.

As for air not moving through the coke bottle region, sorry that's just plain wrong. One only has to look at flow viz / dirty cars to see the air flows through there. It's why the teams make so much effort sculpting the rear of the side pods to encourage air through there.

It's also worth remembering, of course, that the air isn't moving, the car is. The air is effectively still until the car gets to it.

I think the term "fast" is a problem. Fast would suggest that it's faster than the air below the diffuser. If that were true you'd have lift and not DF. The air under the car is squeezed, therefore it accelerates to get the same amount of air through the bottom as the top. Good air flowing, I think, is a better way to say it. The more air you can get to flow over the top, the faster the air undernath will be and the more DF generated.