Wind tunnel talk 2012

[Lycoming]

I thought sauber built the tunnel before BMW, and BMW, seeking to outright own a team as opposed to a simple partnership as they had with Williams, bought sauber in part because they had just built a brand new state-of-the-art wind tunnel?

[marcush.]

yep.
Sauber had conducted their aero workk in Emmen Switzerland (the facility wher Audi and Bentley did lots of their Sportscar work)
and in times when tunneluse was unrestricted they had difficulty allocating the required recources there.So they built their own .

[hardingfv32]

They could purportedly put in two full size cars one behind the other (to simulate backwash aero).

Two models...

"Sauber's decision in favour of a longer than standard layout for the test section was based on a specific consideration. This layout allows two models to be positioned one behind the other, enabling slipstream and air turbulence simulations."

http://www.f1technical.net/articles/47

Brian

[PlatinumZealot]

did you say backwash? haha that has a different meaning. Fluid flowing backwards.

I suppose you mean wake.

[MadMatt]

yep.
Sauber had conducted their aero workk in Emmen Switzerland (the facility wher Audi and Bentley did lots of their Sportscar work)
and in times when tunneluse was unrestricted they had difficulty allocating the required recources there.So they built their own .

Yes, and facilities in Emmen are Ruag's facilities as I wrote a bit earlier.

[marcush.]

What about that ,,windshear" test?When will that occur?After Bahrain they said something like ,,next week we have windhear test, then Mugello, and then Barcelona".I'm a bit confused.
English is not my native language and I can't translate ,,windshear" quite good.Is it aerodynamic test?

viewtopic.php?p=339125#p339125

windshear is a Windtunnel facility in USA able to accomodate full scale cars-you put the real car into the testing area .As i understand this is the sole facility with full moving ground to allow real cars to be put in .

http://www.windshearinc.com/services/se ... m#Services

http://www.windshearinc.com/photos/images.htm#images


The AUDI Climatic Windtunnel we have heard of is also full scale but it cheats a bit when it comes to moving ground:

it has 5 separate belts http://www.media.dimido.de/10/12/offtop ... ns_004.jpg

[MarkedOne8]

Thanks marcush.What about 60% windtunnel scale rule by FIA?What that exactly means comparing to this 100% scale windtunnel test in Windshear?

[Crucial_Xtreme]

Thanks marcush.What about 60% windtunnel scale rule by FIA?What that exactly means comparing to this 100% scale windtunnel test in Windshear?

Part of it is in the article you posted back on page 46.

“The wind shear test falls under the designated amount of testing we’re allowed to do during the course of a year. The rules allow four days of on-track aero testing restricted to 100km per day, which can be exchanged for wind tunnel testing. We chose to swap all of our allotted on-track aero testing for one big hit of wind tunnel testing. We did this last year and found it to be of significant benefit”

They can swap days of 60% testing for one day of full scale.

[marcush.]

Thanks marcush.What about 60% windtunnel scale rule by FIA?What that exactly means comparing to this 100% scale windtunnel test in Windshear?

Inevitably you wil get scaling effects when not testing the real thing.this might or might not be significant but just consider effects of aeroelasticity ..how can you be sure your designs translate from 60 to 100% ...it´s surely a significant error factor -considering the tiny improvements they are looking for.

For small teams the trouble starts right at the beginning-you need everything made in 60% .so that´s a big expenditure and not a cost saving when first running everything in 60% ...

[hardingfv32]

it´s surely a significant error factor -considering the tiny improvements they are looking for.

1) Your sure the scale issue is a significant error factor? I will have to research that position.

2) Windshear is the only 100% tunnel with a rolling road that is available for commercial testing. There are two other OEM units with the same or better capabilities.

Brian

[marcush.]

it´s surely a significant error factor -considering the tiny improvements they are looking for.

1) Your sure the scale issue is a significant error factor? I will have to research that position.

2) Windshear is the only 100% tunnel with a rolling road that is available for commercial testing. There are two other OEM units with the same or better capabilities.

Brian

I remember the Bentley lmp designer -who did work in the Swiss tunnel that sauber was using before setting up their own mentioned this in an interview:

We always polish the surfaces with our model as this is giving the best correlation to real world behaviour...a phenomenon not explainable as polishing the real thing as no measurable influence on the real thing... peter elleray ...was the guy.

I think the interview is to be found on mulsannescorner if i remember correctly.

[hardingfv32]

So far I have found there is a whole field of science called 'Scaling Laws' that relate to anything the is not tested at 100% scale. Also something call 'similitude'. Techniques to test the validity of various scaling formulas, etc. Scaling does not require a directly related analytical solution, just something that accurately correlates the model to the 100% object.

Nothing directly on point to possible wind tunnel errors cause by the us of 'scaling laws' though.

Brian

[marcush.]

how difficult is :building a correct scale radiator in 60% giving the correct flow ....and producing the correct heat output ....I have the feeling adding scale to it just increases the potential for errors in the development .

I imagine getting things correct to about 10% maybe you are ok ,but that is also possible with cfd...

[Crucial_Xtreme]

So far I have found there is a whole field of science called 'Scaling Laws' that relate to anything the is not tested at 100% scale. Also something call 'similitude'. Techniques to test the validity of various scaling formulas, etc. Scaling does not require a directly related analytical solution, just something that accurately correlates the model to the 100% object.

Nothing directly on point to possible wind tunnel errors cause by the us of 'scaling laws' though.

Brian

Couple reasons why full scale can be better than scale model:

-Flow instablility issues. The accurate modelling of track Reynolds numbers can be achieved, and hence real world track condition can be mimicked.
-Aeroelastic effects. Aeroelasticity relates to the interaction of the aerodynamic forces acting on a surface and resulting deformations of its structure. Cunning manipulation of these effects can produce significant reductions in lap time. Only a full scale test can accurately model both aerodynamic and structural effects simultaneously.
-Detailling of small components. Fine detailing of aero sensitive areas of the car can produce substantial gains in performance. A full scale test facility allows the aerodynamicist the best opportunity to fine-tune geometry without the worry of scale effects.

[hardingfv32]

This faith in a 100% tunnel is not well founded.

Using a 100% wind tunnel to test a F1 car could have as many accuracy issues as testing with a 60% model. There are simply no 100% tunnels big enough to do testing without blockage issues. Note the effect on the model when tested in the two sizes of test chambers.

Brian



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