dave
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Posts: 23 
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Post by dave on Nov 10, 2009 11:53:05 GMT -8
Is there a consensus on what shapes are the best for combustion? I know it depends on what you are using for materials. If fire brick, then it is going to be somewhat square. But if you are casting it with refractory cement, what is your choice?
My first thoughts are that square, or even rectangular, will add turbulence in the corners and slow down the flow thru the burn chamber, allowing more complete combustion. However, flows through circular ducts tend to flow most in the center, with a slow moving buffer along the walls. This COULD act as an insulating cushion of air. Plus, circular shapes, of the same square inch of square or rectangular, have less surface area for it to lose its heat. Maybe circular in the burn chamber and rectangular for removing the heat in the exhaust?
If you are concerned with too fast of a flow in a circular chamber, couldn't you put some "dents" in an orderly fashion to mix things up? You could put 2 dents directly across each other on opposite walls to squeeze the outer gases in, then above that put 2 more dents located 90 degrees from the first pair to squeeze the gases the other way.
Just random neuron firings here.
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Post by Donkey on Nov 10, 2009 16:50:12 GMT -8
Interesting question and good points.
Seems to me that if we plan on casting shapes, in the final analysis, we will find more advanced usages out of round ones, or at least curvilinear ones (at least in the burn area).
Nature doesn't make many rectangles or squares and her forces/action(s) tend to act on the curve, rectilinear shapes tend to break down MUCH faster than curvilinear surfaces, as friction and other laws of nature do their work.
When we look to other advanced (and some not so advanced) combustion technologies (and pressure tech., high, low or otherwise), we find that they have taken advantage of nature's tenancies and designed rounded and/or curvy shapes. Compressed air motors, Pelton wheels, rocket engines and jets come to mind.
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Post by canyon on Nov 11, 2009 0:46:17 GMT -8
My random neurons are firing along the lines(or curves rather) of Viktor Schauberger these days as well. I'd like to try a spiral rifled shape tunnel perhaps with a few thick stainless bars spanning cross sectionally (similar to what Ernie posted that he has been trying at the top of the riser) or I really like the heart shape turbulator that Donkey imaged (is that a word?). I think turbulators or vortexizers and tunnel geometries are a great outlet for creative juices that might produce some incredible results. I'd love to play with it but it will have to wait a bit with me as I have some other priorities right now. If anyone else is experimenting please share! (thanks so far to Donkey of course for his tapered heat riser etc. work!) Thanks dave for the thread!  |
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dave
New Member
Posts: 23
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Post by dave on Nov 11, 2009 7:11:45 GMT -8
How about the transition from the burn tunnel to the combustion chamber? Other's experiences have shown that a rough transition is good. If you did a round system, you definitely need some sort of "rifling" to get a swirl going. Just wondering if the flow may still be too fast, barring having to go to a much longer chamber to give it time to burn.
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Post by Donkey on Nov 11, 2009 13:55:09 GMT -8
There are lots of ways of creating turbulence. Sudden expansion, rifled parts, objects in the flow..
Mixing of air and fuel is the aim... How you get there??? Try it and see.
Funny Canyon, that you mention Schauberger.. I've been thinking about him too recently.
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Post by gorbull on Nov 14, 2009 17:34:07 GMT -8
I was thinking about this too. Any reason a square barrel on top of a square heat riser would not work as efficiently as a rounded barrel?
As for creating turbulence what about using a galvanized culvert as a heat riser?
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Post by Donkey on Nov 14, 2009 20:59:45 GMT -8
I was thinking about this too. Any reason a square barrel on top of a square heat riser would not work as efficiently as a rounded barrel? Why not?? Should work just fine. Galvie gives off toxic fumes when heated. |
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Post by swizzlenutz on Nov 15, 2009 16:03:34 GMT -8
Will galvanized give off toxic fumes continuously or will it eventually burn off? Swizzle
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Post by Donkey on Nov 15, 2009 18:30:39 GMT -8
I think it will eventually burn off.
You could probably put (say galvie pipe) in a fire (outside) and burn off the galvanization completely before using it in a stove.
It would be good to find out from someone who knows for sure.
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