Formula 1 Suspension Aerodynamics

Since the mid nineties the aerodynamics of the suspension was more related to drag reduction. However the Tyrrell 024 represented a step change in thinking. From then on the front suspension was considered more and more important for its aerodynamic function and less so for its vehicle dynamics.
This video analyses how much the role of aerodynamic bodywork over the actual suspension arms has on the rest of the car. Building on previous CFD experiment in other videos here the result was a 11.5% improvment in downforce of the rear wing.

[@interfleet522]

But in formula 1's greatest tradition, it was swiftly banned. True words

[@rolandotillit2867]

Check out the flow structure @ 4:07 behind the rear wheels, in the 'inboard loaded(problematic)' frame. Notice how it's dragging down the rear wing tip wake, swallowing the beam wing tip vortex, and the diffuser corner flow. I think a huge amount of performance is in that region, and that a heavily inboard loaded front wing strengthens the flow structure in the rear wheel because it connects with the upper wheel vortex shed off the front wheel.

[@rolandotillit2867]

To save you the trouble of looking it up, positive stagger on bi-planes, or the top wing forward of the bottom wing when viewed from the side, ( anti-dive setup of the control arms) generally creates more lift on takeoff, which tends to agree with your simulations.

[@GianTorress]

I don’t know your plans for this in the future, but it would be cool to see you revisit designing the floor after seeing some of the floor concepts that teams are using.

[@nelsonphillips]

These videos are about trying to understand the aerodynamics of these cars and not just having a guess, I do that on twter. I have my theories about the floors that I would love to test and will likely do it eventually, but they are surprisingly complex and thats not even considering the modelling.... I'll see how I go, but hopefully, it will be a deep and difficult dive though.

[@minascholevas]

Hi Nelson! Engineering student here! I want ro achieve same quality of cfd as you. What is your workflow in openfoam what plugins do you use? Where can I learn more on how to achieve similar simulations?

[@nelsonphillips]

My use of OpenFOAM isn't outside the standard except I do use adaptive mesh refinement. Postprocessing has been knowledge built up over years, I'm not doing anything difficult here its just finding existing functions. I find things that I thought I should have found years ago..... Willem Toet has a good standard to follow for postprocessing

[@fam.hunger5244]

Great Video! Very interesting! Thanks a lot!

[@nelsonphillips]

👍

[@rolandotillit2867]

@7:48 There's a counter rotating pair of vortices in your new simulation. One shed off the front wheel, and the other on the inboard side of the radiator inlet leading edge. Those two vortices are likely entraining air to flow over the sidepods with a bit more energy.
In the old simulation the front wheel vortex is basically hogging the sidepod area.

[@nelsonphillips]

There is also more interaction between the side of the headrest and halo junction with the sidepod. Really the front of the sidepod now just works better, everywhere.

[@rolandotillit2867]

@@nelsonphillips That could be a reason why F1 cars run anti-Ackermann, the inside wheel doesn't turn in as much and doesn't move the tire vortex inboard as much. Meanwhile the outside wheel turns more which drags the vortex outboard.

[@nelsonphillips]

@@rolandotillit2867 Anti-ackermann is mostly to do with tyre deformation, the outside deforms more than the inside so there is a difference in actual slip angle. It took me an embarrassingly long time to know that.... The percentages are so small I doubt that they would change it for downforce rather than just consider it in their analysis.

[@rolandotillit2867]

Correct me if I'm wrong, according to this, the trick is to redirect the front wing upwash into the undercut via the control arms? Reminds me of Bi and Tri-plane design, where you consider the decalage and stagger of the wings. I figured as much and this kind of supports that line of reasoning.

[@williamchayer1266]

The redirect you are talking about seems to correlate with the structure Mercedes has on their upper control arm…

[@nelsonphillips]

This video tested both extremes, one that made the flow worse impacting the sidepods and the other is resolved, though it maybe over resolve with too much lift. There was a brief shot of the RB in the wet, last race, with streaks moving up the chassis after the suspension. With the push rod the coupling of the upper arms are stronger and also the chassis bodywork can be added, unlike the pull rod layout. The amount of flowvis I have seen on the element means they are paying close attention to this area. But, I think its just a minimisation exercise, something you can get wrong rather than performance adding.

[@rolandotillit2867]

@@nelsonphillips Interesting concept. One would wonder what the effect would be if the flow moves above the chassis, especially under yaw. Maybe the benefit of keeping the flow next to the chassis is that it doesn't cross over to the other side of the car as much in the corners?

[@nelsonphillips]

@@rolandotillit2867 That would be Ferraris strategy, and RB was the first to run the cannon cooling exits, so I guess. If you notice with the comparison scene of the whole car with streamlines that flow just around the side of cockpit near the halo junction there is now less front wing influence. This could give me the opportunity to see how much I can reduce the losses of the cockpit and therefore how important controlling the losses in yaw would be without actually running yaw simulations.
I think I need a team of surface modellers....

[@rolandotillit2867]

@@nelsonphillips Your CFD does show higher CP at the entire cockpit, side pod undercut section with the fixed arm profile. Considering how low the pressure is after the floor fences, that pressure differential could be useful downstream.

[@Jay-nk6dm]

2:33, why does the push/pull rod have the effect you mentioned on in and out flow of air? Wouldnt that just be determined by the fairing itself, and couldnt you just change the angle of the fairing on the pull/push rod to get what you wanted?

[@nelsonphillips]

both actuators want to be directing air down as a primary function of their aerodynamics to counter the front wing upwash. A pullrod will also inherently be pulling air outboard, a pushrod will not if the primary function is the same.

[@Jay-nk6dm]

@@nelsonphillips I took a look at the FIA rule book and it says for front suspension fairings that the fairings can only be 10 (nose down) - 0. How can there be any down washing with that?

[@nelsonphillips]

@@Jay-nk6dm geometry is defined by space, whereas angle of attack is defined by air. The geometry of a aerofoil can have lift and has an amount of downwash even at 0 angle of attack. -10degree geometry can in this case be 0 angle of attack

[@Jay-nk6dm]

@@nelsonphillips understood.
Question I had for you though is if you look at many of the teams, the suspension fairings state -10 (nose down) to 0 degrees angle of incidence to the z-plane, yet all teams clearly have downwashing (nose up) fairings.
How is that possible?

[@nelsonphillips]

@@Jay-nk6dm its going by the way you measure angle of attack for the geometry, afaik f1 won't change that. An airfoil profile will alway tangentially outside the -10 to 0 degrees by the fact its a closed geometry and has all the angles, see my video about airfoils for the circulation concept. there are plenty of sim tools like this nasa one, there are better www1.grc.nasa.gov/beginners-guide-to-aeronautics/foilsimstudent/