Vortex Experiment: Can Vacuums Create a Vortex?

[Keith_McClary]

I set up two canister vacuum cleaners facing each other:

I had the idea that if there was some circulation in the air (provided by the small fan) then a vortex would form between the inlets. This does not seem to work. I don't have much knowledge or intuition about aerodynamics. Would this work if I arranged a more symmetrical air flow? (The hoses are in the exhaust ends.)

 

[Fervent Freyja]

Where did you get this idea from?

 

[Keith_McClary]

Where did you get this idea from?

There are various tornado machines described on the web based on a vacuum fan and providing rotation to the air. I thought it should work better with a vacuum at both ends. I tried to google this, no luck.

 

[Fervent Freyja]

If this is even supposed to work... how are you going to know if a vortex forms? Try throwing powder on it to see what is actually happening. Instead of the small fan, maybe a smoke machine directed at the center?

 

[boneh3ad]

It's not clear to me exactly what you are hoping to achieve here. Undoubtedly there will be vortices that form somewhere in that flow system, but whether they are the sort you are looking to create is another question entirely.

 

[RonL]

I love fried bacon (extra crispy ) so I would probably make smoke that way, hobby supplies might have inexpensive machines (or method) for smoke. Try to find some method of diffusing the air coming out of the vacuum, you need the least amount of air turbulence possible in the room. I would like to help more, but I'm a master "thread locker" and would likely start talking about "Tesla Turbines"

 

[Keith_McClary]

It's not clear to me exactly what you are hoping to achieve here. Undoubtedly there will be vortices that form somewhere in that flow system, but whether they are the sort you are looking to create is another question entirely.

I'm wondering what happens if you have two "tornado machines" facing each other. Will the two tornados link up, forming a single vortex (line?, tube?, what is the terminology?) connecting the two exhaust fans? This seems like an obvious thing to try, but I can't Google anything like this.

 

[boneh3ad]

I suppose part of the problem would be that I am not sure how a "tornado machine" operates. There are likely a number of different operating mechanisms for a machine to make a tornado-like vortex that I just don't know what you are trying to do.

 

[Keith_McClary]

I suppose part of the problem would be that I am not sure how a "tornado machine" operates. There are likely a number of different operating mechanisms for a machine to make a tornado-like vortex that I just don't know what you are trying to do.

Like one of these
http://amasci.com/amateur/tornbox.html
http://www.facethewind.com/tornsim/open_air/
except I want to put exhaust fans at both ends.

 

[boneh3ad]

Well for one, it wouldn't do much since you would have two outlets and no inlets, so eventually it would just set up a chamber with a partial vacuum. Either the motors would just keep running without moving much air and they may burn up, or your chamber would fail due to the differential pressure inside versus out.

 

[Keith_McClary]

Well for one, it wouldn't do much since you would have two outlets and no inlets, so eventually it would just set up a chamber with a partial vacuum. Either the motors would just keep running without moving much air and they may burn up, or your chamber would fail due to the differential pressure inside versus out.

There are angled slots to let air in and provide rotation:

This was easy to make once I found a box the right shape.
When I suspend a small binder clip on a thread in the center of the box, it spins rapidly (not so much when above or below the center).

This seems to indicate a strong vortex between the exhausts. I am thinking of making an "open air" version similar to the last link above.

 

[boneh3ad]

I mean, there will definitely be vortices in there, as is the case in most real-world situations where you have moving air. The operative question is going to be where they are located and how large they are, and that will depends on so many factors such as the power of your vacuums, the size and location of your slots, and the geometry of your enclosure.

 

[Keith_McClary]

I made this hi-tech probe from tape and baling wire (bamboo skewer also worked).

If i probe near the center line I can see the tape flutter and feel the vibration. The active part is only about 1 cm in diameter. It stays close to the center line, does not wander like single ended tornadoes.
The box is 50x30x26 cm and the vents are about 2 cm wide.