Constant Motion Wind Tunnel

[hardingfv32]

I read that until recently the Toyota wind tunnel facility in Colognet was the only facility with ‘constant motion’ and ‘constant data collection’ capabilities.

Why would this not have happened sooner? What are the implications of a constant moving model? I assume the floor is one issue, but model movement does not seem an insurmountable task at these budget levels.

What is complicated about constant data collection?

Please expand

Brian

[Seamus]

I don't know, but cheers mate! ; )

[youtube]http://www.youtube.com/watch?v=jbwBsAGCMLE[/youtube]

[Jersey Tom]

I read that until recently the Toyota wind tunnel facility in Colognet was the only facility with ‘constant motion’ and ‘constant data collection’ capabilities.

What does that even mean? And where did you read this?

[Pup]

He possibly read it here...

http://thejudge13.com/#Real%20resource%20restrictions?

Interestingly, one of the reasons both Ferrari and McLaren have been using the Toyota wind tunnel facility in Cologne is because until recently it was the only facility with ‘constant motion’ and ‘constant data collection’ capabilities.

In other facilities during a run, the car would be put through various positions – ride height, pitch, roll etc and for each position a pause was required while the car and air flow was stabilised, then the readings could be taken.

Constant motion facilities reduce the amount of wind tunnel on time significantly. However, the move toward ‘contstant motion and data collection’ will deliver a huge increment in data collected – all of which needs to be analysed and interpreted.

Toyota describes it here...

http://www.toyota-motorsport.com/en/ser ... tunnels-en

At TMG we are dedicated to flexibility and true-to-life accuracy, so High Speed Data Acquisition (HSDA) and Continuous Motion Systems (CMS) are available on both tunnels.

In CMS mode, a user-defined programme of ride height, yaw, roll, steer and individual pre-load changes provides continuous motion on a predefined trajectory while the HSDA system is continuously acquiring data at high frequency.

This allows realistic road or track analysis, reducing tunnel time by as much as 70% and increasing the amount of useful data from each individual test compared to standard motion and acquisition systems.

[riff_raff]

Seems like they claim the frequency of their data acquisition system is better than that of any other similar test facility. In the past, the typical procedure used for testing was to set the controls to a specific value and then wait for test conditions to stabilize before recording data. The test data was needed to validate analysis, and since the analysis was based on static conditions, the test data needed to be recorded under similar static conditions.

[thisisatest]

if this means that they move the car's position while the tunnel is running and while they are still collecting data, im surprised then that other tunnels dont do this.
for bicycles, a wheel manufacturer will test its wheel at different yaw angles, 0-30degrees. the devil's in the details:

When we first started publishing data on the 808 we were using the same wind tunnel protocol that everyone else was using, where you start at 0 and yaw outward taking data, but we realized in 2004 that if you yaw out to 20 or 30 degrees and then take data coming back, there is a pretty sizable hysteresis gap between the two data sets (you get the identical phenomenon with aircraft wings if you take them past their stall angle) We have subsequently changed our protocol to use the 30-0 data instead of the 0-30 protocol after finding that unless you take the wheel all the way back to 0 and let it stabilize, the wheel will continue on the 30-0 curve and not the 0-30 curve, which tends to predict lower drag. This is how you see lens disc data with negative drag, on the old protocol, this would happen about 1 in 3 runs with that type of wheel but was not consistent, after switching to the new protocol we had not seen negative drag in over 200 hours of tunnel time until we had that negative 80 with the disc prototype this february, it was particularly exciting as we had all assumed that negative drag was essentially not possible on the new protocol, and we repeated that data point 2 more times to make sure.

from Josh at Zipp, Slowtwitch.com
http://forum.slowtwitch.com/gforum.cgi?post=1360347;

[scarbs]

Its largely because teams didnt need that level of efficiency until the RRA and new aero testing restrictions came in. Before speed of the run did not penalise the team, except for the cost of electricity in running the fan\cooling. While the only benefit was a slightly more detailed aero map, but that alone wouldn't pay for the investment.
Once the RRA stipulated the 60-40 WT\CFD split suddenly wind on time needed managing. Investing in constant motion\data gathering suddenly had a pay back.

Here's an article I wrote about this for Motorsport Monday http://t.co/BsOZt6fTeu

[gixxer_drew]

Thats a bit of marketing fluff, several tunnels have had similar capacities for years. Some details are unique but I think we should be realistic. That said, the TMG facilities are among the best in the world. They did PIV before a lot of people but even the manufacturer tunnels have PIV at this point. To me the best part about their tunnel is the air speed capacity. Examining the LMP car they did in person, I just felt bad for the aeros. The engine regs forced them to trim out so far compared to Audi and they couldn't really show off their capabilities in the final result.

In response to Scarbs above: IMO, All the development toward mega accuracy high dollar wind tunnel work was spurred by regulation putting engineers inside a box. Domination is found now by gathering VERY tiny increments in a rules box for both resources spent and physical dimensions of the parts. The costs were driven upward for test methods, of course. I wonder when people who write regulations will figure out that budgets are determined by funding, not by regulations. Money just finds the path to greatest performance per quantity of money. Suspension and engine technologies are well established when aero is still rapidly evolving. The maximum aero potential for those dimensions is miles away from where they are trying to control lap times to. Thats how you create a loophole, performance ceiling for the perfect shape vs current regs (control targeting a percentage of that). Any hole in the rules will result in massive gains, that sort of system has that kind of result.

[riff_raff]

Rules that seek to control/equalize costs by regulating the time spent in the wind tunnel or by the amount of digital processing capacity used for CFD work do not understand how the basic engineering design process works. A good aero design engineer will already have refined their design based on experience and intuition long before a model goes to the wind tunnel for testing.

[f1bob]

For those still interested in this subject I've just stumbled across some 'continuous motion' technical information.