An object airfoil shape, if propelled foreward, creates regions of high pressure below the wing and low presure above. The low pressure operates like a vacuum and essentially "sucks" the airfoil upward. Were an airfoil to be strategically engineered and located, could it produce passive vacuum pressure for a moving system? Take for example, auomobile exhaust systems. In gasoline engines, low exhaust presure is beneficial for boosting horsepower. Could an airfoil somehow produce that low pressure, assuming the car is traveling foreward? What about an airfoil ring placed at the end of a rear-facing exhaust system? Given engineered spacing between the outer surface of the exhaust pipe and the airfoil ring, could that airfoil ring produce a region of low pressure that could promote high exhaust flow?
-- imthatwillguy, Dec 23 2002

In many cases, the gyro instruments in aircraft of the past were powered--spun--from vacuum created by an externally mounted venturi tube. If you were to slice such a venturi tube in half along its length and then examine one of the halves you would see that the shape through which the airflow is conducted is much like that of the top of an airplane wing. In this way, a venturi tube is very nearly as your idea title implies: a circular airfoil.
-- bristolz, Dec 23 2002


thanks for all input, this was a brainstorm following a jolly mockery of a fellow attempting to sport a chevy coupe that (from the sound) seemed only to have high preformance exhaust. I enjoy automobiles and thinking....and thus my diarhea of thought
-- imthatwillguy, Dec 23 2002


I have had this same thought, my thinking was to mout the exhaust tip so air would flow around it, creating low pressure behing the exhaust tip and "sucking" the exhaust out, simmilar to when you blow across the top of a straw.
-- Toyman, Nov 19 2003


I too always thought about doing this. I don't see why a venturi wouldn't be able to create a suction to the exhaust, how ever slight it may be. Interesting concept. If I still had access to a metal lathe I would be very tempted to 3/4 bake this... It would be hard to tell the diffrence. Maybe you could run the car on a dynometer and then run a leaf blower through the ventruri.

BTW - I would suggest changing the title to something like 'ventrui assisted exhaust' or something. Your title simply describes a venturi, which is definately baked.
-- KLRico, Nov 20 2003


Toyman was so far the closest. If you turn the exhaust tips down, so that they are parrallel to the ground effect air passing under the body of the car, the flow of air that passes past the open end of the exhaust causes a suction, or scavenges, the exhaust from the exhaust system. This is why some of the older high performance cars of old have side exiting exhaust, where the tips have been cut parrallel to the body surface, that and it looks cool.
-- carguy, Apr 19 2004


Why not simply suck very hard and inhale all the exhaust gases?. Some guys can do hard vacuum.
-- finflazo, Apr 19 2004



random, halfbakery