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### Cyclonic Vacuum Jet

Posted: Wed Aug 21, 2013 10:12 pm
Hi all,

This is an idea I've been mentally toying with for quite some time; spawned from my experimenting with cyclonic separators with air/water for my job.

For those who are not familiar with 'cyclonic separators', or 'cyclonic dust separators' as they are sometimes referred to: http://www.simerics.com/gallery_cyclone

They are a geometric means of separating materials based on density; I added that link solely because it very clearly shows the flow characteristics. What it doesn't necessary address on that site (a google search will show you anything else you want to know about them), is that there is suction provided at the axial tube opposing the conical exit to induce a cyclone; the tangential inlet is not pressurized but drawn in.

What fascinates me about this relative to a pressure-jet is the fact that the level of vacuum provided at the one outlet is positively correlated with both suction at the tangential inlet and, more significantly, pressure output through the second outlet (converging conic section). If we use the bottom outlet as an venturi ejector for the top, we will be creating an ambient/negative pressure zone in the core, through which new air/fuel is pulled in. The tangential inlet swirls the air/fuel to act as a "spring" so that the path of least resistance will always be out either top or bottom outlet. Any thoughts?

### Re: Cyclonic Vacuum Jet

Posted: Fri Oct 11, 2013 2:39 am
Anyone? Any thoughts or criticisms?

### Re: Cyclonic Vacuum Jet

Posted: Sat Oct 12, 2013 2:47 pm
I would have to picture how the flow would work in there. Typically these things suffer when the tail pipe is opened along its length. Also there is a length of time when the intake is positive pressure, so the cyclone would have a very short inflow-stop-reverse cycle. In short, pressure drives flow and this is in a constant state of change.

### Re: Cyclonic Vacuum Jet

Posted: Sat Oct 12, 2013 9:15 pm
Hi [PyroJoe],
Thank you for taking the time to look at this and for commenting!

http://www.youtube.com/watch?v=nQQZkGFKTtU <This is a good practical view of air/dust flow through one of these. The flow is similar without the helical baffle this one has; though it does appear to diffuse the flow nicely and could perhaps comprise a flame holder of sorts?

The tailpipe length issue makes sense; though in this case with the second exhaust routed to the venturi/augmenter, it may not produce the same acoustic decoupling as pulse-jet augmenters as it would be grounded to itself vs. the atmosphere. Once again, this I don't know for sure- merely playing devil's advocate.

The flow would indeed be constantly changing; cyclonic separators are known to be so called "high pressure-drop" devices. I'm hoping one positive aspect of this if it functioned would be that the radial velocity of the inlet would help greatly increase its backflow resistance.

### Re: Cyclonic Vacuum Jet

Posted: Sun Oct 13, 2013 2:11 pm
I have wondered in the past if that would help. I had dismissed it at the time because my thinking was that the pressure created would push through the cyclone action and just blow out the intake in a linear way, taking the path of least resistance and destroying/collapsing the cyclone effect. If I were to go about testing I think I would split the tail and possibly the intakes as shown in the designs below. The draw back I see is there is a very real possibility the internal portion of the second tail might melt or erode from high heat. It would be a fun experiment though and a interesting idea.

### Re: Cyclonic Vacuum Jet

Posted: Wed Oct 23, 2013 8:05 pm
Very cool, thank you for the illustration.

It becomes pretty apparent that the tangential port(s) would almost certainly be a preferred exhaust path, and the axial exhaust would probably rather be an inlet as well.