17 replies to this topic

[Pilla]

Im just curious about the relative wind tunnel size of all the teams.

Mclarens new one is only 50% which for a team in there position I would have thaught was quite small

Williams is also 50% (but they are building a new one, what size?)

Ferraris wind tunnel is 65%? but can run full size cars

The wind tunnel that Sauber is building is also designed for commercial uses so will be full size.

How about the other teams?

Why has Mclaren got such a small one?

[Jhope]

Sauber's windtunnel will be operational by the end of this year. From what I gather, you can place 2 full sized f1 cars, one in front of the other, to test the effects of wake on the car behind. As well, it will be a 2 level windtunnel, allowing car manufacturers, or whoever, to rent out the space at a certain fee, while the Sauber boys conduct their testing. Wind speeds in this tunnel is expected to reach 300km/h, making it the closest windtunnel to reaching actual track speeds. What allows the Fan Rotor to create such speed, it the materials it is being made from. It's being made by some sort of carbon composite material, making it lighter and therfore making it spin faster.

[AD]

If I can remember correctly, I believe that Renault can test a full scale car as well. There was big hype when they first built their wind tunnel a few years ago.

[Pioneer]

I am no aerodynamics expert, but IIRC teams use small scale wind tunnels simply because it is prohibitively expensive to do development work in the wind tunnel with the actual cars. They use models, and its again cheaper to make small scale models than full size ones.

[CFD Dude]

Pilla, the McLaren tunnel is only 50%, but it's an adaptive-wall wind tunnel. The profile of the walls and ceiling can be adjusted to correct the pressure differential within the tunnel. According to some techinical papers I've read on it, the tunnel can be 50% blocked and still provide accurate results. This allows McLaren to run a full car in the tunnel if they wish to.

[Pilla]

Originally posted by CFD Dude
Pilla, the McLaren tunnel is only 50%, but it's an adaptive-wall wind tunnel. The profile of the walls and ceiling can be adjusted to correct the pressure differential within the tunnel. According to some techinical papers I've read on it, the tunnel can be 50% blocked and still provide accurate results. This allows McLaren to run a full car in the tunnel if they wish to.

That sounds really cool, but why would they state that it is just A 50% tunnel on there website? I read about all these filters that the air runs through to ensure a total vortex free, sounds pretty good.

What about the smaller teams what do they use? I know Jordan owns a tunnel and Jaguar used to use one in the US, even ARROWS used to own one, what about a team like Minardi? I read on their site that they will have a 50% wind tunnel operational by the end of 2002, but seeing how the article hasnt been updated since and the fact that minardi had to sack its R&D staff (???) I dont really know how accurate that is.

[CFD Dude]

Pilla, I'm not sure why McLaren only list the tunnel as 50%, maybe that's the size of model they generally run in it? If you want to find out more about the adaptive wall technique Svedrup presented a paper on it at the 2000 SAE Motorsports Conference in Dearborn.

I'm sure this is out of date, but Minardi used Fondmetal's wind-tunnel at one time. The Arrows tunnel was a former DERA wind-tunnel and regarded as one of the best tunnels in all of Europe.
http://www.atlasf1.c...p/id/4334/.html They tried to sell it to Jaguar but the deal fell through. Jaguar bought a tunnel that Reynard was already building instead. It was supposed to be identical to the one that BAR used IIRC. I don't think Jag use the Swift wind-tunnel in California anymore.

[Ben]

I think people are cofusing size of tunnel with size of model.

Renault's tunnel can fit a full size car in it, but the blockage ratio is massive meaning the rusults would be very inaccurate. It may be useful to study internal cooling flows though, for example.

It is the blockage ratio for a given model scale that's important. Even with a 60% scale model the Reynolds number correction won't be that good, and maybe McLaren feel that a 50% model (probably a little easier and cheaper to make) with an adaptive wall tunnel is a better solution?

Ben

[Jhope]

I suggest someone pick up the latest F1 Magazine, with Kimi on the cover. There is a nice article in the Paddock Confidential about Saubers new windtunnel. It mentions just about everything the wind tunnel will be able to do once it's up and running.

[daFt]

or you can read about Sauber's new wind tunnel here .

[tim]

The new Williams tunnel will be 100%. There's more about it here.

[desmo]

Originally posted by tim
The new Williams tunnel will be 100%. There's more about it here.

Source for the 100% assertion?

[Christiaan]

Pininfarina has a wind tunnel that you can fit an F50 into. They have very very advanced instrumentation in there too. I do know that it costs more than twice the capital to build a 100% tunnel to a 50% one. There are many disadvantages with 50% tunnels and the main one being the complexity in getting dynamic similarity. I saw a model Toyota built for a 25% wind tunnel and it had a wierd aspect ratio as well as all sorts of distortions to acuieve the similarity. You'd be surprised to find that a 50% model is not much cheaper that a 100%. Most models are made of cheap resin cast from plaster of paris moulds (I can't confirm if this is the case for F1 though). The cost is usually in setting up the instumentation for the model and now with rapid prototyping you get standard instrumentation units which can be used over and over again with minimal hassle. The Pininfarina tunnel has a module thats about the size of a briefcase that can fit into any model. it contains 160 pressure reading inputs and I think 60 hot wire anemometers for wind speed measurements. It was an infrered link to the main computer where it broadcasts all the acquire data. The wind tunnel is an open jet type so blackage errors are significantly reduced. They also use a laser velocitimeter (technolgy prioneerd by NASA) for flow visualisation.

[pabs]

Particle Image Velocimetry maybe? That would qualify as flow imaging, not visualization...subtle but important difference. And it wasn't developed by NASA. PIV has been around for a few years. The most important contributor to PIV is probably Dr. Ron Adrian from U of Illinois at UC.

[Matt Davis]

I have seen some minardi vans parked outside the windtunnel at university (southampton), on several ocasions including during a GP weekend, but I am not an aero engineer so I don't know anything about the tunnel.

[mulsannemike]

None of the models I've ever worked on were made of "cheap resins". The standard Reynard Champ Car model was based around an Aluimnim spine with carbon bodywork. Test pieces were anything from plastic to aluminum, to one-off carbon bits. Proper aero. bits were anything from machined aluminum to again, carbon.

[desmo]

The following is an excerpt from Peter Wright's book "Formula 1 Technology", which I recommend all to read:

"The 50% wind tunnel models of F1 cars are constructed to the same or greater precision than the full-size cars, and the cost approximately the same. They are built around a central structural spine, and the entire shape of the car is modular, such that any part that is licked by the airstream can be changed. Between the spine and the mounting strut is a six-component, strain-gauge balance mounted within the spine. The balance measures the three forces and the three moments. Also mounted within the spine are multi-channel electronic pressure sensors or scani-valves, for sequentially sampling pressures on the model. The position and attitude of the model car and the incidence of the wings and flaps can be remotely changed via stepper-motor actuators in the model.

Suspension is fully detailed and articulates as the model changes attitude. Brake cooling ducts and the wheel uprights are aerodynamically correct and embody airflow measuring sensors. Radiators are represented by matrices with the same pressure drop characteristics as the actual radiators and are also fitted with airflow sensors. High-pressure air is fed to an ejector within the model, drtiving an airflow that draws air from the engine's ram intake and exhausting the enhanced flow through fully representitive five-into-one exhaust pipes. Any surface can be pressure tapped, but it is the front and rear wings and undertray that are of particular interest. CNC machined from aluminum, pressure ports are laser-milled into them, such that it sometimes seems that an aluminum-eating cousin of the woodworm has taken up residence inside the components. The attachment points incorporate a manifold system, and these key components can be changed without the need to replumb the multiple pressure tappings. Other bodywork parts are often made in CFRP, laid up in CNC-machined tools. Rapid prototyping techniques are being employed widely to make model parts such as exhaust systems.

Wheels are mounted on their own force measuring systems, external to and not touching the model. They run on the moving belt and are supported by rollers beneath the belt to prevent a local heat buildup due to friction. Their drag forces are measured by their mounting system, but lift forces can be taken only via their support rollers which do not provide a precision measurement due to the presence of the belt.

Data from the sensors is multiplexed, the model being one node of a network that forms the data and control systems for the whole tunnel complex. The streamlined support strut, locating the model to the roof of the tunnel, houses the power and data wiring loom and the duct for the ejector air. A typical test run will involve the 30-40 test points needed to compute an aeromap of ride heights and will take approximately 20 minutes. The whole control of the tunnel and test is pre-programmed into the central computer. Fan startup, airspeed, moving ground startup, belt speed, boundary layer control, belt suction, air temperature, model position, force and pressure data sampling, tunnel shutdown, data analysis, and plotting are all computer controlled via the network. Test results are available seconds after a run, enabling aerodynamicists to make judgements about results prior to subsequent tests."

Full size aeromapping is still done. Since the ban on active suspension, as far as I know the test runs are done with the suspension fixed and only a single test point can thus be measured per run. Runs are done outdoors weather permitting. A very smooth stretch of track is necessary. These results are needed to validate and calibrate the wind tunnel results. An active suspension, or at least active ride height management would be most useful for full size aeromapping, even if the systems cannot be run in official testing sessions or races.

[DOHC]

Originally posted by desmo
The following is an excerpt from Peter Wright's book "Formula 1 Technology", which I recommend all to read:

Agreed. It's a great book. It's easy to read, and has an enormous amount of interesting details, also in a historical perspective.