New GM Wind Tunnel
 

Press release on GM's new scale wind tunnel in Warren:

New GM Wind Tunnel Accelerates Fuel-Saving Designs

http://www.wired.com/wp-content/uplo...4-1024x768.jpg

From the article:
I've suspected that part of the GM bail out years ago included an agreement to make cars like the Volt.

I have read that Ford received stimulus money for simply converting light truck plants into making smaller fuel efficient cars.

These events were way back in 2009-ish (some tied to American Recovery and Reinvestment Act of 2009).

I'm just wondering if this facility is an outcrop of that funding, or more of a response to the heightened fuel economy requirements on the horizon.

2012
Obama Administration Finalizes Historic 54.5 MPG Fuel Efficiency Standards
https://www.whitehouse.gov/the-press...iency-standard
Not just cars, heavy trucks too.


2014
White House to Toughen Fuel Standards for Heavy-Duty Vehicles
President Obama Announces New Fuel Economy Regulations | TIME.com

If anyone finds an article linking government grants and or loans to the building of this new wind tunnel please post it. For now it's just a suspicion of mine based on previous events.

Some (Industry Lobbyists) may have felt it was unfair to hike up standards which may impose a financial burden on the car industry, without some vehicle/means/government guaranteed loans to help reach these goals.

Excluding the politics of regulation, the idea of 3D printing scaling down the costs of running different models though it at a more rapid pace is news worthy to say the least.

What is that, a wind tunnel for ants? :)

1/10 scale up to 40% scale models
 

GM's Reduced Scale Wind Tunnel latest testing facility and their 'Honey I've shrunk the kids' models are not just the exterior shells but also include 3D printed highly detailed engines, moving suspension hardware and detailed underbody contours to properly test functional performance on a rolling conveyor road/belt system. Aero-thermodynamic analysis of the component cooling and under body flow effects can also be tested. The downscaling allows to test the new model designs up to 155 mph. The old-school clay models have a limited test life as they eventually dry out, change shape and are destroyed. The new super-realistic and quicker prototyping with ABS, PC or ULTEM thermoplastics are more accurate, durable, repeatable and stable over time.

Anything a kid could get in and pedal around is 1/4th scale, not 1/10th. And it's at the lower limit for the 4 load cells.

Rolling road only between the load cells? Reverse tricycles are just right out.

I think 1/6th scale is the smallest you can go with boats, ships and hovercraft/SES scale model testing.

This 40% scale number in the article is the max-size.

So does this also mean a lower power draw when doing the testing ?
Wind tunnels are huge power hogs.

And that financial burden gets pushed directly to consumers.

I'm already baffled as to how normal people can afford a new car. Even with seven (Seven!!!) year car loans, the monthly costs for a typical new car are far too high for me to justify. It seems impossible to me for the median household income (~$52k) to buy a median priced car (~$33k).

It would sure be fun to work there! :eek:

A 40% scale model has 6.4% (0.4³) the volume of a full size model. 3D printing something with 6.4% the volume is certainly faster and cheaper. The tunnel is smaller too. I think that's the major advantage here, the whole process gets cheaper.

Hey! We are out of paper towels! Crank up the wind tunnel!

No indication of how high the ceiling is, but that's a scale 5 lanes wide. The Darko wind tunnel OTOH has a cross-section more like a carport.

I suspect the cost to run the tunnel is the same with or without anything being tested.

That would be a feature of the Dyson wind tunnel.

Are they increasing the air pressure in the tunnel? Or do they just multiply the air speed to compensate for the scale of the models?

tunnel air speed
 

I don't have my calculator,but I'm thinking that at 40%-scale,they'd run about 50-mph airspeed to simulate 20-mph at full-scale.Otherwise the Reynolds number wouldn't be high enough to transition the boundary layer.

I noticed that too. You could fit a full size car in that thing.
I really do hope it is more efficient.
Large wind tunnels use several MEGAWATTS of electricity.

I seem to remember ( was it Aerohead ?) someone posting that when some of these large scale / supersonic tunnels are powered up, the lights used to dim in the area, due to the power draw ! :eek:

ceiling height
 

At the article website there are a number of photos of the tunnel.
One shows Nina crouching at the tunnel nozzle jet with smoke wand and model.You can see that the nozzle is probably only as tall as Nina.
The test section is 'open' and enormous,but the model is only occupying no more than 5% of the jet cross-sectional area.(outlined in blue)

Why is it that most tunnels are in a huge room ( the University of Toronto, and the one that Ford has come to mind ) and others like the DARKO and A2 are in a small car port sized tunnel ?

why
 

There are a number of tunnel designs and each has specific merits.
A large,open test section allows a lot of maneuvering near the jet,plus low blockage ratios,and the ability to yaw the vehicle.
For straight up drag measurements,as long as buoyancy factors,and boundary layer thickness is addressed,smaller,less expensive tunnels (Pinifarina for example) can return drag and lift data as accurately as the 'monster' tunnels.
1,800-hp is a lot cheaper to run than 18,000-hp or more.
Hucho has an entire chapter devoted to tunnels.
Alan Pope's ,book,'Low Speed Wind Tunnel Design' goes into detailed design.

You can compare the new tunnel to the full size tunnel in Google Maps...

Google Maps of tunnels

New tunnel is on the left.

Link work?

It works for me (in this browser at this time).

It's basically a plenum with bellmouthed inlets and outlets. Not a bad strategy.