"Tornado" Shaped Cyclone

[John Messinger]

Well, nobody has yet answered that question in the affirmative, so I'm going to guess that no one present really knows with certainty whether it'd work worse, the same as, or better than the conventional shape.

I am coming to that conclusion, however only 173 have looked at this thread so far.

the conventional flat wrap conical shape is much easier to fabricate.

Hold on just a second Semper Fi. Once the molds are made which has a time cost you can spray on epoxy, place fiberglass cloth and then spray on more epoxy. I can see a two part mold: one that contains half the cone, half the upper cylinder and half the ramp. The other mold half would contain the very same, plus the inlet chute. Bolting the two pieces together is all that remains.

Even if it's no better than the conventional shape, you'll have a cyclone for your shop. And, in the absolute worst case, it's performance turns out to be significantly worse than the conventional design, replacing the cone with a conventional shape will be simple and you'll have had the fun of trying something different. The reason I'm in this hobby is for the fun of building things, not for ownership of the finished product.

I concur!

[Chris Padilla]

I still like to see a sketch of exactly the shape you are thinking of. Maybe it is so close to a cone that it would likely be fine.

[Frank Hagan]

I like experimentation. Every now and then, someone comes up with something spectacular.

People mentioned Bill Pentz's research ... he has a ton of facts and figures he compiled when he did exactly what you are doing, experimenting to find an optimum solution. He found that many of the cyclones, intended for separating cotton from its seeds, were less efficient at separating dust from air than a different configuration. His site is at http://billpentz.com

At the very least, you'll get tips on how to measure airflow, separation, efficiency and the like to industry standards.

[Daniel Berlin]

At the present second I disagree with #3. I believe that BOTH have the lowest pressure at the top center. The vortex (bottom) of BOTH features high speed air moving horizontally in a circular manner feeding air to a low pressure center core that rises because the pressure is much lower at the center top. However I just poured myself a second Glen Livet.... Perhaps I should stay away from the table saw tonight...

I can tell you your first claim about air pressure is definitely wrong.
The tornado's absolute lowest pressure point is at the center bottom (though the top center is in fact, fairly low pressure as well).

See
http://www.classzone.com/books/earth...=visualization

and
http://www.psc.edu/research/graphics...y/tornado.html

particularly http://www.psc.edu/research/graphics...loseup_cam.mpg
You can see the top center is indeed pretty low pressure, but nowhere near the absolute lowest.

[Paul Atkins]

If you won't try it, I will. Turning a large tornado will be fun. Even if you do, I still might.

[Brian Backner]

John,

Rather than going through the initial effort of building a mold/form for fiberglass, you might want to contact a sheet metal shop with some old timers that have experience with an English Wheel. EW's have been around forever and, short of stamping dies, are the best tool to form complex curves in sheet metal.

Brian

[John Messinger]

I did try the Bill Pentz websites but I could not find anything relating to rejected cone shapes other than he observed that the 1.64:1 length to diameter relationship was important. But I also could not find any "contact us" type of thing to just ask him.

Strike the above, I have just sent him an email.

Addressing Daniel's observations: As far as pressures are concerned, okay yes, it looks like the pressure at the vortex of a tornado is the lowest in the whole structure. However I am willing to bet that both have very similar air flows and similar pressure gradients. Both have a strong updraft in the center and high pressure air coming in from the sides. The difference between them is that the tornado gets its initial spin from the earth's Coriolis Effect, while the cyclone gets its spin from the shape of the upper cylinder and the location of the inlet chute.

[Leigh Betsch]

Probably should consult a meteorologist. Seriously, give it a try, see what happens then let us know. But make sure you know how you will measure the results.

[John Messinger]

Probably should consult a meteorologist. ...

Anybody out there from Kansas?

[Paul Atkins]

Anybody out there from Kansas?
Or "Anybody still left in Kansas?"

[Ken Garlock]

At the present second I disagree with #3. I believe that BOTH have the lowest pressure at the top center. The vortex (bottom) of BOTH features high speed air moving horizontally in a circular manner feeding air to a low pressure center core that rises because the pressure is much lower at the center top. However I just poured myself a second Glen Livet.... Perhaps I should stay away from the table saw tonight...

John, you make a good point. The DC cyclone is "tuned" to force a downward motion on the air/debris entering the cyclone. Clearly the fan causes a strong upward directed low pressure without which nothing would happen. However the fans low pressure is concentrated in a pipe feeding the fan. The downward circulation I was trying to point out is the circulation of the dust/debris toward the bottom of the collection bin.

Second, I found this item on a University of Texas website that supports the upward flow of air inside a tornado.

Stolen from: http://www.tsgc.utexas.edu/stars/tornado.html

How do tornadoes form?

Before thunderstorms develop, a change in wind direction along with an increase of wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere. Rising air within the thunderstorm updraft tilts the rotating air from horizontal to vertical. The area of rotation, 2-6 miles wide, now extends through much of the storm. This rotating column of air, known as a funnel extends from the cloud and grows downward toward the ground. Once the funnel touches the ground is becomes a tornado. Since the center of the funnel is a low pressure area, air rushes into the column and rises. The air is cooled as it rises and water vapor condenses to form the familiar funnel shaped cloud. As the rotating winds begin to pick up dirt and debris from the ground, the funnel will darken. The strongest tornadoes occur in supercell thunderstorms which can also produce large hail and strong downbursts.
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In any event I think we are in the same ball park, John.

Isn't it about time for the maple sap to start running?

[Frank Hagan]

Is a tornado is the wrong "model" for a dust separator? A tornado picks stuff up and carries it along with the air flow, even cows and possibly Helen Hunt (who looked OK, even when in distress and hanging onto a water pipe).

In a dust separator, isn't it the centrifugal force propelling heavier objects to the outside of the swirling air mass, where they contact with the sides of the container and slide/fall into the collection bin? Isn't the velocity of the air at the outside edges of the swirling mass of air greater than toward the center?

Its already been mentioned that the inlet and air ramp force the air to swirl downward and, because the exit is at the top center, reverses the flow at the bottom to exit up through the center of the swirling air.

A cone that is wider at the top rather than having straight sides, might allow the air velocity to slow too much at that wider part to reliably fling the solids to the side, allowing the dust particles to join the slower air exiting the cone.

In any case, the testing should include testing for particles smaller than the visible dust a lot of dust collectors remove, and include those 1 - 3 micron particles that are the most dangerous.

[Jerome Hanby]

Maybe looking to nature is a grand idea, but we're looking at the wrong example. What, in nature, does the best job of sucking up material and dong away with it? I'm thinking you need something about the size of Jupiter and some really good clamps to get started .

[Brett Baldwin]

Jupiter? You're not thinking big enough! Or actually, small enough...I'm thinking a nano black hole is the real solution here. Of course return air is going to be a small problem.

Going back to the funnel idea, it occured to me that the Dyson vacuum guy might like to get in on this. John's approach sure seems to be the same as the way he claims to have worked it out.

[Chip Lindley]

SO you wanna be the first Kid On The Block to have a *tornado* instead of a *cyclone*? WhatEvaa! This thread has not established a what new, efficient improvements you postulate to result from this curved shape rather than the traditional taper. Whaaat?

I know two things for sure! (1) A tapered metal tornado would be a sheet metal workers nightmare! (2) A fiberglass cone would be a static cling nightmare!!