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Post by travis on Jan 27, 2019 18:17:27 GMT -8
So my home made insulative refractory mix was not nearly strong enough and i had to do repairs to my fire box quickly the other day. I might have stumbled on something. I cut the port out of a plain red clay brick but could not make the top square because of the reach of my blade. It ended up being a projection from the top of the port coming to a point at roughly the area of secondary injection. This seems to be helping things run cleaner based on the chimney observation. I have much shorter or totally no time of smoke from the chimney. Anyone else done something like this? It just kind of happened because it had to for the rest of the season. Maybe I'll keep it in other designs. Here is a link to the Dropbox. www.dropbox.com/s/jtpkwkuclc532yh/20190126_120742.jpg?dl=0
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Post by peterberg on Jan 28, 2019 1:41:36 GMT -8
During experiments in 2012 I tried a trip wire and it didn't show any difference at the time. What you did is making the port a bit lower towards the riser as I see it. In effect, the venturi isn't straight anymore but narrower in stream direction. The gas velocity in the port is somewhat higher because of that, which could result in stronger mixing. Just guessing, maybe there's someone who could confirm or correct my assumption.
Thinking about this, I've always worked with straight ports because of the ease of build. It seems to be worthwhile to test a configuration where the sides are also slightly pinching in towards the riser. The pressure difference compared to the air inlet would be greater then. As I see it, seen from the firebox the pressure at one end is higher than at the other, causing a strong horizontal draft. Now I am thinking about it, the port is amplifying the draft of the chimney. Smaller port means stronger draft but also more friction making the system less reliable as I've found out. Even the characteristic roar costs energy and is causing drag.
Thanks for the thought Travis, this is another experiment to test in future.
Chamfering or rounding the corners of the port is utterly wrong as some people, including me, found out.
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Post by satamax on Jan 28, 2019 2:53:06 GMT -8
Peter, i wouldn't taper in the port. Just in case it acts the same as the rounded corners. Flaring out to create big turbulence behind the port could be interesting. Like in this vidéo, round the six minutes something. With the big tapper. youtu.be/rDhSdtMjSpA?t=415
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Post by peterberg on Jan 28, 2019 2:57:08 GMT -8
An experiment can't fail, it's meant to learn from it. Maybe both possibilities need to be investigated. (Not enough time and energy to do all I would like.)
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Post by Vortex on Jan 28, 2019 7:13:44 GMT -8
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Post by satamax on Jan 28, 2019 8:43:35 GMT -8
An experiments can't fail, it's meant to learn from it. Maybe both possibilities need to be investigated. (Not enough time and energy to do all I would like.) Yep Peter, i know. Tho, we know rounding the edges doesn't work. And i guess, funneling in the port might well get the same results, up to 15° i would guess. Gases make a stable cushion on the slant part. Éroded by the gas flow. So the nose is round.
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Post by travis on Jan 29, 2019 0:33:17 GMT -8
Nice, its cool to hear others have done a similar thing. Vortex, its been really great to follow the progression of your stoves as well. Really beautiful work. You made your projection from metal right? Has it held up ok? I would guess it might wear out fast.
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Post by Vortex on Jan 29, 2019 2:54:38 GMT -8
Thanks. It's quarter inch thick steel, the surface is starting to spall but it's ok otherwise. It's only for testing purposes. I'm going to try out some different shapes and whatever is the best will get incorporated into the next set of casts.
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Post by travis on Jan 30, 2019 23:15:49 GMT -8
Nice. Will be cool to see what you find
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Post by hof on Feb 15, 2019 12:04:42 GMT -8
Russians try cone section before port. Looks like working good.
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Post by Vortex on Feb 15, 2019 12:53:37 GMT -8
Interesting. Can you show an example?
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Post by hof on Feb 18, 2019 13:13:48 GMT -8
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Post by Vortex on Feb 19, 2019 2:33:03 GMT -8
Thanks hof, unfortunately I'm not a member of that Russian forum so all I can see is the tiny picture on the first link. I tried to join but cannot get through the registration using a translation. Can you post the full size picture here?
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Post by hof on Feb 19, 2019 3:06:40 GMT -8
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Post by wiscojames on Feb 19, 2019 4:38:11 GMT -8
Well that's interesting. Quite a bit more complexity for the builder, but I'd like to see one in operation using those parameters.
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