3D printed plastic burner experiments (photo heavy)

[Another FrankenBurner]

I am after a tapered iron mix tube.  I designed it in CAD and then 3D printed a pattern and core mold.  We also 3D printed the runner and gates.

 

This cast failed.

If you click on the image to see it's full resolution, you can make out the 3D print lines in the surface finish.  

We decided to make the runner longer, the gates larger, and the sprue tapered.  We CAD it up and printed again.

 

 

3D printing and sand casting are a good combination.  The pattern was easy to produce, splits, and has pins for alignment.  The sprue has it's own alignment pin, it's tapered shape makes it easy to remove from the cope, and the taper gives us a larger target when pouring.  The core mold produces a core which fits the pattern void and has exactly the taper I am after.  

This cast also failed.  We suspect the failure was pouring too soon.  Gray cast iron pouring temperature is several hundred degrees above it's melting temperature and we think we didn't give it enough time to heat far enough beyond the melted point.  We will be patient on the next attempt.  If that fails still, we may have to bring up the wall thickness.

If you are looking to learn sand casting, I highly recommend Dan's website.  I learned a lot from it.  I also peppered him with questions which he happily answered.

While the failures are disappointing, we are enjoying playing in the sand and pouring iron.

[D.Rotblatt]

11 hours ago, Another FrankenBurner said:

We suspect the failure was pouring too soon.  Gray cast iron pouring temperature is several hundred degrees above it's melting temperature and we think we didn't give it enough time to heat far enough beyond the melted point. 

That looks right from the first image of the failed cast - I've had the exact same results with failed casts on bronze that's too thin or the metal too cool.  The differential in the temperature from the molten metal to the mold material is 2500 degrees - the heat gets pulled out of it fast.  With bronze pouring temp is a couple hundred degrees over melting temp too, I allow 5 minutes time to heat after melting (unless I'm impatient...).  You might need more with iron because it's pouring temp is closer to the temp of the forge. Seems it's the opposite of aluminum, which has problems if it gets too hot.  With Bronze it doesn't matter if its a little extra hot, you'll have to see with iron.

Head pressure will also push the iron into the mold, but your pouring sprue looks plenty large and high, so I don't think that's the problem.

With good sand casts you can see finger prints - it's gets surprisingly fine detail as long as the sand can release well.

I'm impressed that you're pouring iron!  Never did that, but you are making it look easy.  I also like your use of tongue and groove to make the box alignment - good thinking!

DanR

 

[D.Rotblatt]

TINKERING UPDATE:

Great success today!  I tried two ideas we had talked about, and both helped.  I got the bronze burner up to 2290F.  The Reil went up to 2230F.  The cast burner also ran well with a .046 mig tip.  Here's what I did:

On 8/30/2019 at 9:13 PM, Another FrankenBurner said:

With the Bordeaux modification, you have got some straight pipe before the convergent section.  I wonder if this is helpful to the Reil burner performance.

I simply ran some tape around the bronze burner to make a lip.  One width of tape didn't do much, but two did (standard sized blue tape).  It was rough, but the sound changed and the flame became more lean.  I had a small choke plate, and i put it on.  Mikey, the sweet spot for this was with the choke plate about 1/2-3/4" back from fully closed.  If I moved it back or forward it didn't seem to change the quality of the flame much, but the temperature went down.  Might be a mixing thing.  It occurs to me that if I am putting a tube on the back of the burner, I can put fins on the choke plate that extent to the edge of the tube (i.e. the choke plate is about 1" diameter, while the tube is 2" diameter).  

 

On 9/1/2019 at 9:20 PM, Another FrankenBurner said:

as the length of channel is increased, beginning with a sharp edge, the gas rate rapidly increases and reaches a maximum at a certain length of channel and then gradually decreases.

I also tried shortening the MIg top to about .3".  This was also very effective.  With a long .046 mig tip, I got a very rich flame.  With the shorter tip the flame became much hotter and leaner.

Off to bed!  Was a good day.  Now to play with some new designs that add a 'Lip' before the reducer.  Several ideas come to mind....

DanR

 

[Another FrankenBurner]

On 9/4/2019 at 10:35 AM, D.Rotblatt said:

I'm impressed that you're pouring iron!  Never did that, but you are making it look easy. 

It's easy to make failing look easy but we are getting pretty good at it.   

I am glad to see the improvements in your flame.  I will have to tinker with adding a section of straight before the reducer as well.  I am also following the others down the 3D printer nozzle as an orifice rabbit hole.  

It looks like your tape may be tapered out.  You may have increased the size of the reducer more than adding a section of straight.

[D.Rotblatt]

1 hour ago, Another FrankenBurner said:

It looks like your tape may be tapered out.  You may have increased the size of the reducer more than adding a section of straight.

Nah, it was proof of concept.  I was changing tips over and over, and the tape just got crumpled. It started as a straight tube, and I imagine it will work better if it's not a crumpled mess. Even if it did increase the size, that would be a solution... I'm going to try this one next:

Walls on the side 1" high with a choke that has either 0, 2, or 3 fins on it.  They are all printing up now.  Same trumpet shape as the cast burner.  We'll see how that works.  All of it is castable in sand (although fins are harder, but it's small, I should be able to unscrew it from the sand....).

DanR

[Another FrankenBurner]

Unscrew it from the sand... I look forward to seeing this.  

[D.Rotblatt]

Just give it a few taps to loosen it and slide it out (at least that's the theory...).  In the "old" days, one of the foundry tests was to sand cast a spoon, cup and saucer in one piece. http://schoepp.hylands.net/coffecup.html if you want to see how it's done, pretty impressive.

DanR

[Another FrankenBurner]

Wow.  I will not be attempting it any time soon.

I just finished CAD on v74 which is v46 with a 1 inch straight section before the reducer.  We'll see what happens.

[D.Rotblatt]

I'd love to see.  The straight section after the intake fins?  Your burner is so different that I'm not sure what it will do...will be interesting to see!

[Another FrankenBurner]

Here is version 74.  Straight section is after the intake fins.  I have it printed but have not tested it yet.

 

[Another FrankenBurner]

I tested v74.  It's flame is in the richer range and the secondary flame is fluffy.  Not so good on this burner.  

[G-son]

Tried anything along these lines? Starting with many vanes at a large diameter, probably overlapping each other to really force the air to follow their angle - even if the space between each vane is small the large number should let plenty of air in, and at fairly low speed. It starts rotating rather slow out by the vanes, as it goes closer to the center it rotates faster, and once going down the funnel it might just be a lot faster than in the small diameter versions. Or it might not.

[Another FrankenBurner]

I expect it would have more rotation but at a cost of a air volume.  You used the word force, "really force the air to follow."  I have found that every time I think this way, I get less air.  I now think with the word encourage instead of force.  As stream line as possible with the smallest resistance needed to encourage the air.  

I have forced a bit more vortex than my current golden versions(v46) but it was so much that the flame started to shorten and spread.  A tornado flame.  I don't think that it was productive past a certain point and it cost me air volume.

I think the vortex helps with the mixing more than air volume.  I have a few versions of burners with less vortex which exceed the air induction of v46 but their flame color is not nearly as uniform in color and the flame is not as violent/turbulent sounding.  The v46 flame has enough spin still in the stream that the flame is shorter, bushier, and louder.  

The other thing that probably works against your idea is the air induction does not behave the way we think it does.  Instead of gracefully coming into one air inlet to meet the inside of the next vane, the air wants to pull straight from the outside to the center.  The throat is at a lower pressure than ambient.  Ambient pressure being higher, pushes air in.  Imagine a vacuum cleaner drawing air down the tube.  The air goes as straight to the low pressure zone as possible.  The vanes being angled cause the air to go to one side easier than the other, path of least resistance.  This gives angle to momentum which is the initial nudge to vortex but the vortex only has as much rotation as it has to.

I see something more like the red than the yellow when playing with smoke.  

The other problem I see with this idea would be supporting the long flats while printing.  I could use supports but then I wouldn't know how to get them out it.  I could print in two pieces and glue them together.  

Of course, I could have it all wrong.  Hopefully I do.  I will give it a shot.  It's a good test of my understanding of things.  What OD were you thinking?  

[G-son]

You have some interesting points. Would be very interesting to see an actual test.

These vanes is more along the lines of what I was thinking, with overlap so the air must go diagonally between them - the large total area of the openings compared to the mixing tube should still mean there's little restriction to flow. Once it's moving that way, it's easier for it to keep rotating than to change direction straighter towards the center - or that's my theory anyway. 

I can't quite tell what OD would seem right, but say something like 2x funnel diameter to the inside of the vanes, and then let the vanes have as much size as they need at an angle that looks good and gives them enough overlap to direct the air around, preventing the air from going straight towards the center. In this picture it looks like 3x funnel diameter may be good for outside diameter, but better drawn in a more aerodynamic shape that might change a lot.

[Mikey98118]

12 hours ago, Another FrankenBurner said:

Of course, I could have it all wrong.  Hopefully I do.  I will give it a shot. 

I think you have it exactly right.

[D.Rotblatt]

23 minutes ago, Another FrankenBurner said:

Not so good on this burner.

Our two burners are different beasts. 

I ran another temperature test with my burners.  Same jet assembly (except on the reil burner), and same 5 lb gas pressure exactly (used the ball valve to turn it off, same forge.  Tried a quick test of my ribbon burner vs a straight single burner (the ribbon burner was far superior - a couple of hundred degrees).

A summery of the results:

-The new burner (3D printed with 1" lip), with a choke without fins was the best so far getting to 2300F.

-Adding fins to the choke on the new burner decreased the temperature.

-The Ribbon burner far exceeded the single nozzle burner with the same injector assembly (the bronze cast one) by 200F. 

_____________________________________________________

The results of the test are below.  The set-up is 5lb pressure, .046 mig tip  ( trimmed to about .25" long), Modified NA ribbon burner (the one with 1/8" holes described in the NA ribbon burner section).  I used the same jet set-up (which is removable) and just swapped it out between the test rig for the new yellow burner, and the bronze cast burner.  Each test was allowed to run until the temperature stabilized.

Bronze cast burner - 2260

Yellow Burner with 3 fin choke - 2268F

Yellow Burner with 2 fin choke - 2272F

Yellow burner with choke (no fins showed below) - 2300

_____________________________________________________

This is the best test.  New burner on test rig with plain (no fin) choke:

     

____________________________________________________________

I also ran the burners with the ribbon burner out of the forge.  Larger flames on the Yellow Burner injector.  I got pics and can post if you like.

DanR

[Mikey98118]

The reducer shape of the air inlet will make a vortex. Whether we use impeller bladed computer fans, or fin shaped ribs between air intakes leading into the reducer, we are only trying to encourage the vortex to form a little faster, by introducing swirling air at the reducer entrance.

This was intended as my two-scents worth on the previous discussion; not anything to do with Dan's post.

[D.Rotblatt]

13 hours ago, Another FrankenBurner said:

I expect it would have more rotation but at a cost of a air volume

 

19 minutes ago, Mikey98118 said:

I think you have it exactly right.

What I am finding in my experiments tinkering is that it is all about volume, not creating a vortex.  Contrary to prevalent opinions, I am finding that any fins or blockage seem to decrease output.  It may be that I haven't found the "sweet spot", but so far the results have been consistent with this observation.  It may be that the funnel shape of the burners creates enough of a vortex that the gas mixes "good enough" and is already in that sweet spot.

Given that, I will try one more experiment with a larger diameter funnel and choke with fins so the area of intake is consistent with the one I have now with no fins.

DanR

[Another FrankenBurner]

12 hours ago, G-son said:

These vanes is more along the lines of what I was thinking

I kind of figured this was what you were thinking.  The squirrel cage of sorts.  I tried forcing vortex for quite a while.  Here is one such post.

I think the airfoils still face the same problems.  You mentioned having a large enough OD so the air is not restricted and enters slowly.  If the air is coming in nice and slow, it will go around your vanes headed as straight as possible for the middle of the low pressure zone.  For the air to move the way you are thinking/wanting, it would have to have higher velocity.  Without a powered supply, the only way to accomplish this would be to restrict the inlets sectional area which will lower air volume.  Also as your OD increases, so does the length of surface the air has to pass along.  One last thing that I saw in one of my experiments, because the air was pulling around my vanes sideways to what I originally thought, I saw eddies on the inside concave part of the curve. 

I am not trying to poopoo your idea.  I like ideas.  I will CAD it up and we will see.

1 hour ago, Mikey98118 said:

I think you have it exactly right.

You are always there to encourage everyone.  Thanks Mikey.

1 hour ago, D.Rotblatt said:

Our two burners are different beasts. 

They are indeed.  Different applications dictating different demands.  Probably why we have such contrasting results.  Which is great.  I am trying to bridge the gap.  I would love to get away from investment casting for the fun/easy/quicker sand casting.  I will follow whatever does the best even if that means investment casting.  At the moment, I can't seem to beat v46 and I am up to v75 at this point.  

I keep playing with burners of similar proportions to yours but minus the ribbon burner.  I see similar results in induction increase but with what I interpret as poor mixing.  I can't seem to eat my cake and have it too.  Your plenum/ribbon may be doing all that wonderful mixing for you.  It may explain your 200° difference.  

2 hours ago, D.Rotblatt said:

I got pics and can post if you like.

Yep.  All the information we can get.

[G-son]

9 hours ago, Another FrankenBurner said:

I am not trying to poopoo your idea.  I like ideas.  I will CAD it up and we will see.

I've been involved in some online discussions with experts in the discussed field (engine tuning), where one expert often just replies "That doesn't work!", and when anyone tries to ask about more details not he gets xxxxxx off and suggest anyone doubting what he said to try for themselves (which would require some expensive equipment that normal people don't have access to).
You give great answers, with your reasoning very clear, no matter if you agree or not there's something to learn and new knowledge to base future ideas and theories on. The answers from the so called tuning expert I mentioned were on the other hand rather useless, I'm sure he was right about that specific case, but not knowing any of the logic behind it it's impossible to try to apply that to any other slightly different situation. Constructive criticism is great, even if the idea turns out to be useless. 

[Another FrankenBurner]

Yes, we have all dealt with that guy.  For me that usually means I am talking to an engineer.  That is not an expert thing, that's a personality thing.  They know too much to be bothered with questions.  I have met a few actual experts.  They were truly experts in whatever field and knew nothing of anything else.  The ones I dealt with were nice and didn't mind being peppered with questions.    My relentless curiosity in everything means I will never be an expert in anything.  I'm ok with that.  I suppose learning is my passion.  The more I learn, the less I know.

Here is a start, version G1:

It's my guess at what you were thinking.  Anything you want changed?  Taller vanes, different shape to the vanes, larger OD, larger reduction radius?  If you have a different idea, I can work with hand drawings.  

 

[Frosty]

1 hour ago, G-son said:

Constructive criticism is great, even if the idea turns out to be useless. 

When a reporter or biographer I don't recall, asked Thomas Edison how it felt having failed tens of thousands of times trying to make a light bulb work. Edison replied to paraphrase, great, I now know tens of thousands of ways a light bulb won't work.

In the same light, the guy tuning jet engines had the expensive equipment both subject and test. He'd probably learned that people who don't have either have ideas of limited use, good or bad. We see similar on IFI, a new guy asks a question and we see any number of guys with as little knowledge or experience answering it. 

Not that you don't get some brilliant ideas from folks who's opinion is unpolluted by knowledge, unfortunately new insights or good ideas from that sector number a very small fraction of a percent.

I'm not tossing a dog in that arena, just offering a view. 

About the drawings of intake vanes though, I have an observation to offer. I'd considered the idea for inducing a vortex in a burner tube but experimenting with tin cans and smoke showed me they have little effect except to restrict intake flow. As mentioned already the smoke is pushed into the low pressure zone following the rules of simple physics. EG. Force always follows the path of least resistance. Which is straight towards the center of the low pressure zone.

The vanes as drawn here leave gaps with a straight path towards the center and so the air is focused into the more narrow paths by the vanes rather than deflected in the desired direction. Smoke showed very little flow sideways but quite a bit of turbulence around the vanes disrupting flow more so.

What I found I had to do was make the intake fan almost two layers. The vanes had to completely block a straight path to the center of the low pressure zone. The vanes had to be long structures with complete overlap. Think 5 vanes that are at least 25% of the circumference each so the only path for intake air is in the desired direction. 

I tested with my air hose as primary (jet) and a piece of plexiglass in the choke plate position so I could watch smoke. 

While I was able to make a strong vortex the device had a weak flow. 

I was playing with ideas I got from that box of brochures, etc. and early day web searches when you could access patent servers directly without pages of persistent ads. The drawing I remember of a burner that induced a strong vortex introduced the primary through a spinning jet. There were versions of both gas and fuel oil burners though the mechanism to induce the vortex were different. The propane drove a mechanical fan where the oil was sprayed into an electrically driven fan. 

The stated purpose of the strong vortex was to prevent direct flame contact with the furnace liner and heat exchange tubes. The Burnham oil boiler in my basement uses a high pressure, vortex driver oil jet.

I'll say right now I'm far from knowing if a good vortex can be induced in the intake air rather than just encouraging it to develop naturally. I don't know, I only experimented a few times and went with the easy build T burner.

My thoughts may not have enough information behind them to count for much.

Frosty The Lucky. 

[D.Rotblatt]

10 hours ago, Another FrankenBurner said:

Your plenum/ribbon may be doing all that wonderful mixing for you.  It may explain your 200° difference.  

I’m running all these on a rest rig with single nozzle as well and comparing flames, but I agree that the right angle and plenum aid in mixing. But that said, I feel the temp difference between single and multiple nozzles is in better combustion. A single nozzle burner has a central flame cone of ~4” long and 1+” wide, while the multiple nozzle flame core is about 3/4”long and 1/8” wide. These small flames are also sandwiched between other flames. In a single burner the flame isn’t finished combustion when it hits wall or floor, while the ribbon burner flame is completely combusted half way to the floor (mine points directly down).  This does support the need for better mixing in single nozzle burners which in turn support the benefits for inducing a strong vortex.

Just kind of thinking out loud here...

DanR

[G-son]

1 hour ago, Another FrankenBurner said:

Yes, we have all dealt with that guy.  For me that usually means I am talking to an engineer.  That is not an expert thing, that's a personality thing.  They know too much to be bothered with questions.  I have met a few actual experts.  They were truly experts in whatever field and knew nothing of anything else.  The ones I dealt with were nice and didn't mind being peppered with questions.    My relentless curiosity in everything means I will never be an expert in anything.  I'm ok with that.  I suppose learning is my passion.  The more I learn, the less I know.

Here is a start, version G1:

It's my guess at what you were thinking.  Anything you want changed?  Taller vanes, different shape to the vanes, larger OD, larger reduction radius?  If you have a different idea, I can work with hand drawings.  

 

I have yet to meet one of those engineers, the one I've talked to didn't have that habit. Although that was back when he was studying and some time after, it's been a few years so things may have changed.
The "jack off all trades" tend to be interesting to talk to. Lots of insight into many areas. 

The drawing is close to what I'm thinking. A little longer vanes to increase overlap, and a bit taller vanes to increase inlet area past the vanes to reduce the risk of restricting the flow there, and it's perfect! (Or, so I hope. If it fails I can call it a perfect failure, I'm not picky. )

[D.Rotblatt]

14 hours ago, Another FrankenBurner said:

I would love to get away from investment casting for the fun/easy/quicker sand casting.

After making the last casting with a core, I’m thinking that a sand cast of your burner head is absolutely doable.  The core is basically the funnel with fins, a brass tube to hold it on center.  Doable....

DanR