Cleaning the flow behind an F1 car?

[gridwalker]

I don't know who did the study ...

I do believe that was a Mr Nick Wirth, using the same CFD technologies that he is now applying to Virgin GP.

See here : http://www.grandprix.com/ft/ft20831.html

[kilcoo316]

I don't know who did the study ...

I do believe that was a Mr Nick Wirth, using the same CFD technologies that he is now applying to Virgin GP.

See here : http://www.grandprix.com/ft/ft20831.html

Good find.

I note also from that:

At the time the Technical Working Group, working with the Grand Prix Manufacturers' Association (GPMA) used the Italian Fondtech wind tunnel, run by former Ferrari and Tyrrell aerodynamicist Jean-Claude Migeot, to see if the CDG wing would work. Migeot and his team concluded that the idea was flawed.

[kilcoo316]

It is the central airflow which is almost laminar that is used to clean the diffusser wake, not the trailing vortices from the two wings.

Laminar flow would not exist in the volume/area between the wings.

[slimjim8201]

Thoughts on the following proposal:

1. Restrict maximum angle of attack for wing elements and diffuser exit angle.
2. Increase tire width.

I believe these changes, while not revolutionary like the CDG wing concept, would have a significant impact on the ability to overtake. The end result would be less turbulent downstream wakes and a shift in the aero-to-mechanical grip ratio towards the latter. Either one of these could spawn more passing opportunities.

[tok-tokkie]

I don't know who did the study ...

I do believe that was a Mr Nick Wirth, using the same CFD technologies that he is now applying to Virgin GP.

See here : http://www.grandprix.com/ft/ft20831.html

That summary of the entire OWG examination of the challenge was extremely informative. Why can't they implement it in 2011? Is it purely the double diffuser that defeated their work?

[wesley123]

what i thought is that underbody tunnels instead of an diffuser have alot cleaner airflow exiting, what if you take 2 tunnels at the car centerline? that would develop possibilities and also makes the underbody less 'important'.

[Just_a_fan]

The need for tyres that don't create marbles all over the off-line part of the track is also important. Indeed, the marbles are one of the biggest problems as they prevent cars running side-by-side in keya reas that would facilitate a driver attempting an overtake.

Making the tyres much less soft would also reduce the amount of detritous they would pick up off line which would also reduce the penalty of being offline.

Having a tyre that creates a single line around a track is always going to make overtaking difficult because anyone off line will be at a big disadvantage straight away - indeed it also contributes to the reluctance of lapped drivers getting out of the way too.

[kilcoo316]

That summary of the entire OWG examination of the challenge was extremely informative. Why can't they implement it in 2011? Is it purely the double diffuser that defeated their work?

Agghh. Look, they probably used a RANS turbulence model - loads of damping - so the predictions were skewed, the subsequent windtunnel tests showed it wouldn't work, and I for one believe a good tunnel test far more than I believe a CFD prediction.


(And I say that as someone getting paid to do CFD simulations for very large aerospace companies)

[autogyro]

The bottom line is that FOTA and the teams are preventing the extensive work that still needs to be done to find the answers.
The FIA are also to blame for not placing far higher pressure on F1 to achieve this result.
Current aerodynamics in F1 is slowly destroying the sport and is also responsible for wasting huge amounts of money.
The lack of overtaking and poor spectacle is the direct result of a greedy reluctant few, who should know better and refuse to force the needed change.

Why cant the teams and the FIA work closer together and get a bl--dy move on before it is to late.

[Germanengineering]

Well...

http://www.fia.com/mediacentre/Press_Re ... 05-01.html







---

I say enforce rules which ask for simpler front/rear wings, and of course, single diffusers. Also bring back the 2 metre wide tracks (pre-1998 wide cars) which offer better mechanical grip I believe.

Your basic idea is to reduce reliance on downforce and increase mechanical grip, rather than going for a more complex idea of having a nicer wake.

I think...

Max wanted this design to increase overtaking. I think this would great.

[LegendaryM]

I think the FIA should enforce a downforce limit, not by say 15,000N max downforce as teams will try to have 15,000N of downforce at low speeds, but limit it by lift coefficent. This would ensure teams worked towards reducing drag which over time would improve the wake of the car.
All the other ideas, except for spec aero (if that happened i would stop watching f1) would increase overtaking for the first few races, but it would become increasingly more difficult to overtake as teams clawed back downforce. A downforce limit would ensure that the wake should continually improve as drag reduces, so overtaking continues to become easier

[autogyro]

I think the FIA should enforce a downforce limit, not by say 15,000N max downforce as teams will try to have 15,000N of downforce at low speeds, but limit it by lift coefficent. This would ensure teams worked towards reducing drag which over time would improve the wake of the car.
All the other ideas, except for spec aero (if that happened i would stop watching f1) would increase overtaking for the first few races, but it would become increasingly more difficult to overtake as teams clawed back downforce. A downforce limit would ensure that the wake should continually improve as drag reduces, so overtaking continues to become easier

I like the basics of that LegendaryM. They should look into that idea.
How do you measure the DF easily to enforce a limit?

[wrcsti]

I think the FIA should enforce a downforce limit, not by say 15,000N max downforce as teams will try to have 15,000N of downforce at low speeds, but limit it by lift coefficent. This would ensure teams worked towards reducing drag which over time would improve the wake of the car.
All the other ideas, except for spec aero (if that happened i would stop watching f1) would increase overtaking for the first few races, but it would become increasingly more difficult to overtake as teams clawed back downforce. A downforce limit would ensure that the wake should continually improve as drag reduces, so overtaking continues to become easier

I like the basics of that LegendaryM. They should look into that idea.
How do you measure the DF easily to enforce a limit?

Ive thought of this idea for years and have to say the problem is enforcing it. Only way would be a pottable wind tunnel capable of runing around 150mph constant wind velocity.
Best way to increase overtaking is to slow the cars down to touring car speeds, at these speeds everything has to work so well that any outside force will hust the cars performance. Either that or run cars with ground effects only and no wings.

[DaveKillens]

How do you measure the DF easily to enforce a limit?

Keep it simple. Just have a rig that pushes down on the entire car with a specific weight. Then set up the plank to contact the ground at that setup.

If during the race the downforce exceeds the limits, the plank will contact the ground.

[tok-tokkie]

That summary of the entire OWG examination of the challenge was extremely informative. Why can't they implement it in 2011? Is it purely the double diffuser that defeated their work?

Agghh. Look, they probably used a RANS turbulence model - loads of damping - so the predictions were skewed, the subsequent windtunnel tests showed it wouldn't work, and I for one believe a good tunnel test far more than I believe a CFD prediction.


(And I say that as someone getting paid to do CFD simulations for very large aerospace companies)

To have a constructive discussion it is necessary for both parties to know what they are talking about. You, unfortunately, appear to be pronouncing on an article you have failed to comprehend or, more likely, failed to read. Here are some of the bits you have missed:

Critically, in complete refutation of what you have just claimed there is:

Between March and September 2007 there were several sessions in the wind tunnel, with Byrne doing much of the hands-on work and all sorts of ideas were investigated. The final configuration pretty much hit its targets though baseline drag fell by 10 per cent.

It appears you are referring to the CDG wing, this is where it came from:

In 2005 FIA President Max Mosley commissioned his former partner Nick Wirth, a designer who had worked with the Simtek and Renault F1 teams, to come up with an idea of how to lower aerodynamic turbulence behind the cars and by doing so create more overtaking. Wirth worked with computational fluid dynamics (CFD) programmes to come up with what he called the Centreline Downwash Generating (CDG) wing. The FIA announced that it would introduce the CDG wing in 2008.

A few paragraphs later there is this:

By the autumn of 2006 no-one had much confidence in the CDG wing and Mosley agreed that its introduction could be delayed and that the Technical Working Group should come up with a better idea for 2009.

As a consequence the Overtaking Working Group (OWG) was formed.

Pat Symonds of Renault, Rory Byrne of Ferrari and Paddy Lowe of McLaren were all well-established engineers of repute and all were keen to get the job done using commonsense and a scientific approach. The OWG met for the first time in January 2007

After quite a bit of simulator & wind tunnel work (please note no CFD) they could say:

"Almost all of the attempts to reduce downforce in the recent past have been retrograde in terms of overtaking possibilities and wake behaviour," one member of the OWG said. "If we had wanted to make overtaking chances worse, that was what we would have come up with."

Here is their finding on the original Nick Wirth proposal (that one illustrated in this thread with 2 wings behind the wheels and no wing between designed using CFD):

Nick Wirth's computational fluid dynamics (CFD)-generated rear wing had eliminated the central section altogether, effectively comprising instead two separate rear wings, to eliminate the upwash, but the OWG concluded that this was the very reason that it did not work.

The article was written in October 2008. It is noteworthy that the designers of the three quickest cars did that work in co-operation.