Questions on Ribbon Burners

[Frosty]

That is screaming hot, nice I like it. I get it now, the floor plate was either acting as a resonator / sounding board or the burner was rattling it at it's own harmonic.

The burner song is sounding like a whole bunch of little burners "roaring" together in a chamber. Smaller the burner the higher the pitch and lower the volume. My NARB burners are quieter than single nozzle T burners because the nozzles are smaller. NARB are driven with as exactly the same T, inducer mixing tubes as my single nozzle burners. I in fact unscrewed the thread protector from my shop forge burner and screwed it to the NARBs to test. 

I could live with your forge's song. I kind of like it even. I don't know how to stop it though, I believe it's 12 little burner nozzles roaring in harmony. Maybe experiment with more, smaller nozzles until their roar is a whisper to our ears? There are IFI members who've made burners with lots of 1/16" nozzles and they burn very well. 

Frosty the Lucky.

[edennis]

That all makes sense. I find it interesting though that in the previous burner configuration (close to a right angle pointed down), there was zero vibration. 

[Frosty]

Now the flame path is across the kiln shelf and is either finding a way under the close edge or perhaps causing lift like a wing. Maybe a little of both.

Straight down the flame path is pushing down in the center and the flow to the sides is across opposite trailing edges. It should be pretty self damping eh?

Frosty the Lucky.

[Buzzkill]

4 hours ago, edennis said:

I'm a little stumped by the harmonic problem still. I think it must have to do with changing the burner from a right angle to a tangent

I've had the "harmonic howl" on the last several naturally aspirated ribbon burners I've built.  I definitely get it on the burners that are side mounted.  I think I also got it on the one I had that was floor mounted.  For me it's temperature and pressure dependent to some degree.  Back pressure seems to also play a part.  One burner I used was sensitive enough that the noise would change when I walked in front of the forge. When I first fire up the forge I get a constant howl for a few minutes from the burners that displayed this "feature."  By the time the interior is glowing the howl goes away for me.  Another thing I noticed is that the ribbon burners I've built with a lot of small diameter holes were more prone to the phenomenon than those that used a lower number of larger diameter holes.  The current one has 180 1/8" holes and it howls loudly enough to be quite annoying at certain pressures when the forge is cold.

[Asuperstar]

I am building my first forge.  I have a ribbon burner and and assembling the inside now.  What I do not see in the help section is what pipes and hoses to buy.  

The outer dimension of my ribbon burner pipe is 2 inches.  It is not threaded.  WHat do I need to get from the end of the ribbon burner to the propane bottle?

[Latticino]

A 2" NPT mixing chamber with a port for your fuel and one for your forced air.  Fuel source with 1/4 turn isolation valve and modulating regulator.  Blower for forced air with some method of varying the flowrate (speed control, waste gate, inlet gate, outlet valve...)