Random Wind Tunnel and Smoke Pictures Thread

[CFECO]

If the Drag increases at the square of the speed, I'd think there would be a Huge difference in pressures and flow, between 40 mph and 70, not even to mention 100+, not that 100 mph is much use to most of us here. I had just never seen what speeds are tested in these photos.

[kach22i]

Old thread on the topic, including links with charts.

http://ecomodder.com/forum/showthrea...peed-6178.html

[aerohead]

Originally Posted by CFECO

At what speed are all these tests done? I'd think if the air was going 100 mph the flow would be much different than if it was going ten MPH. Without knowing the speed for each test photo, they are basically meaningless.

For the lengths of contemporary automobiles,the turbulent boundary layer and Cd are established at around 20-mph and remain constant up to around 250-mph,when compressibility affects kick in.
So a smoke trace photo would look essentially the same between 20,and 200+ mph.
Since the electric motors powering the wind tunnels can be in the thousands of horsepower range,the lower the test section velocity,the more economical the operation.And you can imagine the volume of smoke necessary to even show up at high tunnel velocities.
In the testing section of Hucho's books he shows the specifications of most leading automotive wind tunnels.

[freebeard]

If the Drag increases at the square of the speed, I'd think there would be a Huge difference in pressures and flow, between 40 mph and 70, not even to mention 100+, not that 100 mph is much use to most of us here.

100mph is a worthy goal if you attain and cruise at it economically.

If you look at 3D CDF heat maps, you see they can map velocity and pressure independently. So there are interdependent things here.

The streamlines are persistent between a lower bound (where laminar flow goes turbulent) and an upper bound where subsonic shockwaves start to intrude. This necessarily involves air pressure, vehicle size and Reynolds Number.

[kach22i]

Wednesday, March 7, 2012
Pininfarina Cambiano Concept
Andoniscars | passion for excellence

[kach22i]

Swiss Ski Team Train in Audi Wind Tunnel



Design Storz - Mindset - Car Design News


Bo-Dyn Bobsled Project, Geoff Bodine and Chassis Dynamics together build the USA Olympic team bobsleds - News

Using a stream of smoke, designer Bob Cuneo (standing) gets an idea how bobsled driver Steven Holcomb's helmet and head position affect the performance of the two-man sled.

[kach22i]

997.2 Carrera / S / 4 / 4S / GTS (2009-2012) - SharkWerks Porsche Project Gallery

[botsapper]

Had an industrial design class where we designed personal tents...most would have been gliders with this test. wind tunnel testing

[ennored]

Looks like it would have performed better backwards.

Just had to throw that in. Not quite sure how you set your tent up into the wind not knowing the winds will stay the same all night, but fun test.

[aerohead]

The Federation of Masochistic Backpackers has placed an order for 1,000 units!