Concept for regulations to improve overtaking

[toraabe]

If you read this, you will understand. More groundeffect and less wing.. As I have said before http://www.indycar.com/News/2017/03/03- ... ign-update

[jjn9128]

If you read this, you will understand. More groundeffect and less wing.. As I have said before http://www.indycar.com/News/2017/03/03- ... ign-update

Not to be argumentative but this is not what I have seen through experimentation and data. I went into my research with this notion that underbody is better than wings for following because it's rammed down our throats but the evidence I would say is to the contrary. Also notice the big 3-element rear wing in the concept.

Also what is 'ground effect'? People who continually call for more ground effect through a contoured or tunnel underbody also say the front wing needs to go because it is most effected by a wake - ignoring that the principal 'ground effect' for the front wing is the venturi effect same as the floor.

[Vyssion]

If you read this, you will understand. More groundeffect and less wing.. As I have said before http://www.indycar.com/News/2017/03/03- ... ign-update

Not to be argumentative but this is not what I have seen through experimentation and data. I went into my research with this notion that underbody is better than wings for following because it's rammed down our throats but the evidence I would say is to the contrary. Also notice the big 3-element rear wing in the concept.

Also what is 'ground effect'? People who continually call for more ground effect through a contoured or tunnel underbody also say the front wing needs to go because it is most effected by a wake - ignoring that the principal 'ground effect' for the front wing is the venturi effect same as the floor.

In my experience with designing, I have found this to be true as well. What causes issues is that teams bleed "mis-information" to the viewers in order to distract or just generate a buzz for what is changing.

The interviewee Tino Belli has held quite a few chief and director roles in motorsport (he was at Andretti for like 15 yrs as technical director I think?) and so I do think that he knows what he is talking about, to say the least!! Unfortunately, journalists don't and you only need to look at the fact that this sentence here:

A key component of the new car is for it to generate most of its downforce from underneath instead of on top. This will improve racing and passing opportunities by decreasing the turbulent air that the Indy car leaves in its wake.

Is not actually contained within quotes as being a comment from Belli himself; i.e. it was written by the journalist.
Odd in that that is already the case for almost ALL downforce generating devices; because the pressure differential between the pressure (top) and suction (bottom) side of aerofoils is much easier to increase if the suction side's pressure drop is made greater, than if you try to increase the pressure on top of the aerofoil. And the turbulence left within it's wake is due to the displacement of air in the "force generation" process... Less turbulence could be seen to imply less downforce as well.

As jjn9128 said, a front wing acts more like a venturi / diffuser than an actual wing nowadays (Brawn GP took advantage of this fact in 2009 when they won the F1 championship).

A typical F1 car's wake is characterized by two counter rotating vortices being shed by the tyres curving in towards the vehicle centreline and then upwards. Focusing on "more ground effect aerodynamics" (which I am assuming means "more underbody downforce generation") will not really change this typical wake shape I don't think.

[Just_a_fan]

If you read this, you will understand. More groundeffect and less wing.. As I have said before http://www.indycar.com/News/2017/03/03- ... ign-update

And as we keep telling you, ad nauseam, F1 cars are ground effect cars. The front wing is a ground effect device. The floor is a ground effect device. The car is a ground effect device. F1 CARS ARE GROUND EFFECT CARS.

[jjn9128]

So I've done some CFD and I thought I'd share, because why not. I'm targeting a CzS ~-4 with a CxS ~1 to be representative of a current generation car. Let's just say the car misses the downforce target quite significantly with the main issues being front end and underbody downforce. The front wing is at about 1/3 of target while the body is about 1/10 of target. At the moment the underbody is being hampered by ingress from the front wheel wakes, which I have an idea for how to cure, and I think the lack of cooling inflow isn't helping either. I'm still learning openfoam, it's not so intuitive as powerflow or star, the next step is to add some cooling to the model while trying to boost the downforce to a representative value - before doing (or Dynamicflow doing) some drafting studies.




In regard to what turbof1 asked about wheel wakes and shrouding, this is a series of YZ slices through the wake from rear wheel axle line back. Initially the wake coming from the underbody is quite fast even with the wakes of the rear suspension. Not far after the car the wheel wakes are quite large and are swept towards the centreline before being pulled upwards and away from where it would affect a following car. I think it's fairly obvious that fairing the wheels would go a long way to improving the wake and reducing it's effect downstream. NB: because the underbody isn't producing a lot of downforce its wake is quite high energy. I also have an idea to reduce rear wheel drag, and thus the wake, using the cooling outlets...

[Vyssion]

Just to add to what jjn9128 has given already on F1 wakes, I attended a seminar given by SimScale a month or so ago and posted a summary of the presentation with images here: viewtopic.php?f=6&t=26209. On each slide, the image on the left is the 2016 aero setup, and the image on the right is the 2017 aero setup at each corresponding distance within the wake region.

The car that they used was closer to the current 2017 aero set up that exists now, but is by no means anywhere near as refined and/or produces the same level of drag and downforce as say the Ferrari or Mercedes 2017 cars. I assume that the contour is a plot of total pressure (i.e. energy in the flow field) but I don't have a reference for scaling colours which is quite irritating...

Here are the wake images:

I'm still learning openfoam, it's not so intuitive as powerflow or star...

If you need a hand, I am using OpenFoam for work currently (in the process of convincing the big boss to buy StarCCM) [-o< - let me know

[FW17]

- ignoring that the principal 'ground effect' for the front wing is the venturi effect same as the floor.

The idea of removing the front wing is to reduce the load points. A venturi tunnel designed car will have only 1 point of aero loading which would be the throat of the venturi tunnel i.e the COG of the car. The front and rear aerofoils if present will be used only to influence the balance of the car from front to rear

Tunnels will be better for the car as the disturbance from a tunnel is lot lesser from a diffuser as the wake is lesser or non existent. Tunnels from 80's F1 cannot be compared to GP2 and Indycar tunnels as the 80's tunnels were designed as liner flow taking advantage of the skirts to prevent air from moving sideways. GP2 and Indycar use aero seals by vortex flow(which also adds downforce) adds another dimension to the flow, so the airflow is turbulent as it exits the rear of the car, though not as much as in a current f1 design.

[Juzh]

At least part of overtaking problem is also the power output F1 cars currently have. If you're on the throttle 0.5s earlier, which you are if you're a car in front, you've already gained like 3 cars lengths on the car behind before he's able to floor it, thus negating slipstream for a majority of the straight. This more of less only happens in F1 to such an extent as it has by far the most power of any racing series.

[Ogami musashi]

I'm still not sure if this answered your question?! I think the effect of cornering on wakes and subsequently the wake effect would certainly be a great topic for study and maybe even would go as far as to suggest it is something Brawn and Somerville should look into when defining the new aerodynamic rules.

Thank you jjn, this is an interesting topic indeed. I think it should be studied, and actually, it was studied (albeit only superficially) in the OWG study, where they measured an increase in downforce with some lateral separation, so indeed i am curious if this can happen while cornering. But as you said, asymmetry of inboard and outboard wakes and some possible side-effects of those asymmetries are worth studying imho.

In another post, i suggested using blown aerodynamics to recover dynamic pressure deficit, do you think it could be a viable solution?

[jjn9128]

In another post, i suggested using blown aerodynamics to recover dynamic pressure deficit, do you think it could be a viable solution?

Gosh. That's another interesting question. I am not sure that allowing this sort of active boundary layer control (assuming you mean this not the exhaust blown devises from a few years back) would have a "bolt-on" improvement for the wake of a current spec car - but coupled with a removal of vortex generators and strakes, especially in the diffuser region, it might have a beneficial effect. These two images are taken from Willem Toet's "How do motorsport diffusers work" article/essay. In the second case a VG of some sort is placed near the front of the floor to boost downforce, but the result is that the wake is lower 'energy'. F1 teams take this to the nth degree.

While I don't think it would have a significant effect on boundary layer thickness, flow state, and the wake which results from that; if you could achieve flow attachment in an 'over-expanded' duct like a modern F1 diffuser without the help of vortices then the resulting wake may be 'cleaner' while still achieving high downforce. If used on a rear wing it may be possible to have improved lift-to-drag with higher camber wings - achieving the increased vertical momentum in the wake I believe is required to extract the wake over a following car. The problem comes with the large separated flows behind the rear wheels, which are a big portion of the 'energy' loss in the wake.

The FiA (and formerly FISA) have historically been a bit scared of aerodynamics, not without reason in the past as some horrific accidents were the direct result of either aerodynamic component failures or a failure to properly understand the aerodynamics. But the FiA have not moved on from that fear regarding active aerodynamics, which I think could be implemented safely now, certainly more safely that teams devising ways to work around bodywork flexibility tests. If the goal is road relevance as with the engines (power units) then wings and diffusers are worthless but if the rules were opened up to active boundary layer control or surface morphing this could ultimately benefit fuel economy in future road vehicles i.e. simplify the surfaces and move the investment to areas which could be globally beneficial.

Bit of an aside but that post from Willem Toet highlights the dichotomy between the aims of the regulator and the teams

If I see high energy air exiting the floor of the car (at the most critical low ride heights), I look to find a way of using it.

[Ogami musashi]

I was thinking about blown aerodynamics for the following car actually. In aerospace (especially in military aviation) there's a continuous flow of studies (since the last decade) using either mechanical (suction, jets) or electrical (plasma) means to re-attach fully detached boundary layer (even in high velocity fighter jet engines exhaust gazes) which inevitably leads to the need of re-energizing it to prevent adverse pressure gradients.

Plasma was once considered by max mosley in a , perhaps not so realistic, set of regulation that were to happen in 2011. IIRC, it had to do with the budget caps. In those set of regulations, active aero was allowed (but VG and high camber wings banned) and plasma active flow control was to be used for the following car.

Without going for plasma actuators that require a lot of power, jets or suction devices could work. Active aero would have to be implemented and as you say, i think the fear of active aero should vannish today were you actually lend the responsibility of braking to a computer...

[jjn9128]

I was thinking about blown aerodynamics for the following car actually. In aerospace (especially in military aviation) there's a continuous flow of studies (since the last decade) using either mechanical (suction, jets) or electrical (plasma) means to re-attach fully detached boundary layer (even in high velocity fighter jet engines exhaust gazes) which inevitably leads to the need of re-energizing it to prevent adverse pressure gradients.

Plasma was once considered by max mosley in a , perhaps not so realistic, set of regulation that were to happen in 2011. IIRC, it had to do with the budget caps. In those set of regulations, active aero was allowed (but VG and high camber wings banned) and plasma active flow control was to be used for the following car.

Without going for plasma actuators that require a lot of power, jets or suction devices could work. Active aero would have to be implemented and as you say, i think the fear of active aero should vannish today were you actually lend the responsibility of braking to a computer...

Hmmm I don't think blown aerodynamics would help for the following car. The issue isn't one of flow separation - the pressure gradients on wing surfaces are reduced by the effect of Pdyn loss. I guess another supposition for that is that it is a wake turbulence effect, i.e. a change of flow state on wings, which again it isn't as boundary layers are already turbulent. Do you have any links to that proposed 2011 rule change?

I think a lot of current research in boundary layer control for road cars is in piezo electric actuators.

[Ogami musashi]

Hello,

Blown surfaces are not only for BL reattachment but can be used for direct lift (in the case of planes) just by speeding up the flows.

The 2011 framework as proposed by max mosley. However, i recalled it differently, as obvioulsy here the active flow control is meant for drag reduction. The framework was very much build in a "road relevance" context.
https://www.lfs.net/attachment/33390

[jjn9128]

Hello,

Blown surfaces are not only for BL reattachment but can be used for direct lift (in the case of planes) just by speeding up the flows.

The 2011 framework as proposed by max mosley. However, i recalled it differently, as obvioulsy here the active flow control is meant for drag reduction. The framework was very much build in a "road relevance" context.
https://www.lfs.net/attachment/33390

Thank you for that. It's an interesting regulation proposal. I'm not sure how I feel about it. For one it supposes that the wake effect is 'turbulence' and all the mechanisms for combating it seem to suppose boundary layer separation. It talks about reducing drag and states that open-wheel/open-cockpit are the largest sources of drag, but doesn't offer a means of reducing those drag contributions. I like the adaptive cooling, active suspension, and adjustable aerodynamics and I also agree with it that the way to achieve laptimes isn't always through the Top Gear/Jeremy Clarkson "MOARRR POWAAARRRR" mentality, but through a considered balance of power, weight, drag and downforce.

I'm not sure how I feel about spec components, as they suggest for an FIA developed undertray. On the one hand I can see no benefit in teams throwing millions of pounds/dollars/euros at developing parts that can't be seen - it would reduce costs and also theoretically improve competition, but on the other F1 has traditionally (at least since I have been watching) been a constructors championship. Where does the spec'ing of parts stop - the chassis are all basically the same so why not spec them, suspension and cooling and gearboxes don't significantly affect competition spec them too. The floors on Le Mans prototypes are basically the same, so too Indycar and they have fairly decent racing so maybe it would be good. It's a difficult balance to find and I have trouble coming down on one side of the argument or the other. Overall though I think it would be cool to see these regulations implemented.

[toraabe]

Ross Brawn knows everything about groundeffect. http://www.ultimatecarpage.com/car/4484 ... JR-14.html