Saturday, February 23, 2008

Cool

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4 comments:

Tecumseh said...

Yep: Coanda works for trucks, too:

A researcher named Robert Englar, of Georgia Tech, has apparently invented a way to cut the wind resistance of trucks and buses by a staggering amount -- maybe 65 or 70 percent relative to designs with commonplace streamlining, over 80 percent relative to a design with no streamlining. He did it using the Coanda effect, which is the phenomenon in which streams of air blown parallel to a surface tend to follow that surface as it curves. (The effect is named for Henri Coanda, who experimented with an early jet engine for aircraft, and accidentally set his plane on fire when an ad-hoc heat shield unexpectedly caused the jet's exhaust to cling to the plane's sides.)
On large, boxy shapes like heavy trucks (or sport-utility vehicles), most of the drag actually comes from the back end, not from the end facing the wind. It happens because of all the turbulence in the vehicle's wake. Traditionally, the only way to avoid it is to give the thing a very long tapered tail, like a fish. But by putting a suitably curved flange around the back end and blowing a stream of air across it, the Coanda effect can eliminate much of the turbulence and get the air to smoothly converge behind the truck.

2/24/2008 12:11 AM
Tecumseh said...

Seethe, JJ, seethe!

2/24/2008 1:32 AM
My Frontier Thesis said...

This is an excellent example of taking various OTS (Off the Shelf) components, fusing them together, and doing it at a great deal less than constructing a machine like this from scratch. Glad to see my tax dollars go towards something like this.

2/24/2008 5:47 PM
Pepe le Pew said...

Just in time for the upcoming capitulation.

2/24/2008 10:01 PM

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