Burners 101

[philb86]

1 hour ago, Trevor84 said:

Shall I call you Phil? You are right on the money, it's like you were standing over my shoulder watching me curse.

 

Yes sir, that is my name.  

Mikey, so I finished up the most recent things that you suggested.  Dropped won to a .030 MIG nozzle, and tapered them.  Just couldn't get the pictures to focus like I had been getting them to, guessing due to having both burners going at the same time.  All the pictures of flame that I posted prior are of the top burner in the picture.  I was quite interested in how easily there was a difference on the choke sleeve restricting the inlet ports to get them close to burning the same.  Any ways, pictures are below.

5 PSI

10 PSI

15 PSI

 

Just a couple pictures of the plain burners.  I will eventually redo these, as I wasnt happy with the slots after having to use the grinder to cut out between the holes.  I know that I can get them much more uniform and smoother for air flow if I throw them on the mill and actually mill the slots out.

Forge body and cart I built, still not finished yet.  The stock holder on the front of the forge is adjustable for distance from the forge and height adjustable as well.   Have to weld the top lock collars on to the metal cover to hold the forge burners as well as figure out if I want doors with IFB brick in them, or if Im just going to put angle brackets on the top and bottom to be able to slide two IFB bricks side to side to act as the door on the front and back.

[Trevor84]

32 minutes ago, Mikey98118 said:

The middle opening is smaller than than the two end openings; this creates a whirlpool effect

I never thought about it in this way but said that way I get a good visual, like if it was water instead of air it would swirl just like a toilet. I had envisioned it like two waves slamming straight at each other and tumbling down the mixing tube side by side but nature doesn't work like that. Something has to give and once it does it continues towards the path of least resistance in this case that is chasing it's self down the mixing tube.......... At least that's what my brain thinks it's seeing

 

1 hour ago, Mikey98118 said:

the amount of reduction matters because of spin; not volume

I haven't tried contemplating volume yet, I love math but I am not good at figuring out what I am trying I am trying to calculate.

I reference the surface area of the intake's opening/mouth but I am guessing I am saying this wrong. That reference is just based off the measurements taken off the main burners out there. 

You often see "that guy" with the 12" mixing tube with a 3/4"-1 1/4" reducer for a flare, 2"-1" reducer for the intake then 1"-3/4" bushing ("that's all the had") and then they have the orifice jammed into the throat and wonders why it's not working. If you tell this guy he needs to start over he ends up hooking a blow dryer to it and perpetuates the BS builds. If I throw numbers at him so he can pretend he's making I up as he goes, he basically ends up with something close enough to a real burner that he sticks with the craft and doesn't run around calling some blow dryer mash up a Frosty T.   
 

[Another FrankenBurner]

6 hours ago, Trevor84 said:

I think I remembered something AFB was talking about incorrectly wen I mentioned speed.

  You did not remember it incorrectly.  Or were you saying I was talking about something incorrectly? 

I have seen higher velocities/flow rates with the printer nozzles when compared to a same sized orifice mig tips.  I built a testing rig to compare them when I started using the 3D printer nozzles.  I was originally concerned the 3D printer nozzles would not produce the proper jet as their orifice channel is much shorter.  They ended up producing a nice stream.  I also started shaving length off of mig tips in steps to test the effects, like Frosty does to tune his burners.  The longer the channel, the higher the resistance, the lower the flow rate.  

6 hours ago, Trevor84 said:

I am not arguing just trying to understand, I can almost guarantee that I will never be giving attitude or what not.

Same here.  I like discussions, not arguments.  I don't want to discourage.  I especially don't want to discourage math.  I am not trying to give you a hard time.

The intake section, I could not tell what it was describing.  The way it is written confused me.  Even for area, 1.5-2 x the ID of the mix tube is confusing.  For 3/4" pipe, are you calculating 0.824 x 2 = 1.648 in² or are you meaning multiply the area of the mix tube by 2?  ( 2π(0.824/2)² ≈ 1.067 in² )   

Why express things in rough formulas, rather then giving rough measurements?  Is this so that the advice could potentially apply to other sizes of burners?  

4 hours ago, Mikey98118 said:

Wow! I knew quality was diminishing over the last twenty years, but had no idea it was getting that bad.

The mig tips were two different manufacturers.  I wonder if I bought another brand, if I would find a third size.

[Trevor84]

No ya I remembered incorrectly  I had remembered you had said something about them but got speed stuck in my head instead flow and resistance. So I remembered something that you didn't say.

Ya now see I put this together for Facebookers though, you are thinking about it so this is like Frosty's 3/4"x8 not Mikey's 7/8"x9 (I've seen them go back and forth over that)

Ratios for different sized burners correct. EZ burner .75x2 = 1.5 so 1 1/2" to 3/4". My 3/4 Mikey has 3 openings 1/2"x1"x3 gives me 1 1/2" total opening.

 

Same goes for the orifice depth, I thought it was Mikey a few years ago that said it was .5 x the id of mix tube or it was 3/8" above the throat which is give or take that .5xid. All the burners I have had success with tend to use this depth. 

 

[Mikey98118]

Understand that what I believe about mixture flow, etc. is just my visualization of what I think I understand about the why of things burner. I only insist on my views when it comes down to the how of my own burner design. Some other burner designs, which departed from mine came up with blue ribbon flames. It doesn't matter how people pass the goal line; just that they do so. Whatever works is good enough.

The flame photos only show a little improvement; this is not discouraging, since the MIG tips are the short kind. You want the longer tips in place. I believe that it will turn the corner for you. If you can't find the longer tips, drop down to .025" or even .023" tips. I expect your next flame photos will be perfect, with this last change.

[philb86]

On 1/20/2021 at 1:01 AM, Mikey98118 said:

The flame photos only show a little improvement; this is not discouraging, since the MIG tips are the short kind. You want the longer tips in place. I believe that it will turn the corner for you. If you can't find the longer tips, drop down to .025" or even .023" tips. I expect your next flame photos will be perfect, with this last change.

Mikey,  Here are the final pictures, with tapered .025 MIG nozzles.

5 PSI

10 PSI

15 PSI

20 PSI

Both Burners at 15 PSI

[Mikey98118]

They are much better than where you started and also better than the last set. Lots of guys would stop here. I hope you will go down to the .023". You are right next door to achieving a blue ribbon flame. You're so very close.

[philb86]

1 hour ago, Mikey98118 said:

They are much better than where you started and also better than the last set. Lots of guys would stop here. I hope you will go down to the .023". You are right next door to achieving a blue ribbon flame. You're so very close.

I most likely will step down one more, definitely seems to be less of an intense flame ( not sure if that means anything), and oddly much quieter than when I first started.  Im going to get my hands on some .023 MIG tips, but the weld ship did not have any for some reason, smallest they had was .025.  going to focus on finishing my forge and building a stand for my ASO that im going to use as an anvil for the time being.

Thanks again Mikey, could not have gotten this far without all of your help.

Phil

[Mikey98118]

Actually those flames are growing more intense; the reason they are quieter is that the combustion is happening in a smaller area. You must remember that flame variance is what makes the noise. These flame are varying as much as before, but it is all happening in a smaller space; so, less sound is generated. I believe that once you make the last change to the smaller tips, your flames will turn darker blue, and will be nearly all primary flame, with only a trace of secondary. This will provide complete combustion inside the forge, wants it heats into incandescence. And that is the real goal. 

[Mikey98118]

De-tuning 1/4" high-speed burners to increase turn-down range

Recently someone else on this group built a 1/4" size "Mikey" burner, and departed from my specifications; it turned out better than my own burner! I had given up on my design in such small sizes, because they have insignificant turn-down ranges; or so I thought. His burner makes a single flame envelope, but I can tell from its softer outline, that it can be turned down nicely. What went right for him? He accidentally de-tuned his burner by lengthening the mixing tube length a little bit, and using air openings that were basically slots, rather than rectangles. The result is easier to build, with better overall performance.

  Smaller burners are easier to get hot flames from, but harder to manage. A little de-tuning can be a timely idea, if your hotrod won't stay on the road

[Mikey98118]

Understanding flames

When looking at the flame from a high-speed burner in a cold forge or furnace, It will appear much as it does out in the open air, but within moments it will lengthen and become smoother in outline, as the equipment starts to super-heat; it will also lighten in hue to faintly blue. There will be little to no secondary flame within the equipment, even while it is cold; lesser burners will make more complicated flame envelopes, but this is the ideal; these facts also hold as true for multi-flame ceramic burner heads as they do for single flame burner flame retention nozzles.

    You need to remember that there are at least two different flames going on within the average gas forge or furnace; the flame being input by the burner, and an internal atmosphere, which may extend to an output flame leaving the equipment via the exhaust opening. When blacksmiths discuss terms like dragon's breath it is such an exhaust flame they are usually speaking, or clear hot exhaust gases at best; or blue, or orange to yellow, reducing flames at worst. A very different animal than the burner flame. Not that both flames aren't equally important clues to burner performance, but they need to be treated separately for clarity. So what amounts to a perfect exhaust flame? No flame at all. An exception must be noted: Some refractories will exude orange and yellow flames for a while.

    If we are speaking about the burner flame, straight blue from a single combustion envelope is the goal, but many older burner designs have a white inner flame ahead of a blue secondary flame, followed by a darker larger and less substantial appearing blue or purple tertiary flame from the combustion with secondary air. Buy or build a good enough burner to see no white in the flame, and then tune well enough to have little or no secondary flame.

    The next question tends to be "how dark a blue?" Different fuels give off different hues, and lean flames are always a darker blue than neutral flames in any given fuel. In fact a burner can be run so lean that the primary flame turns purple from the amount of red that excess super-heated oxygen gives it. On the other hand, any slightest tinge of green in the flame is an unmistakable sign that it is way too fuel rich; such a flame will also be pumping out lots of carbon monoxide.

    The simplest way to judge a neutral flame is that it’s blue is a lighter hue, and it has very little to no secondary flame; any darkening beyond that is from too much oxygen; it is called a lean flame as it is thought to be lean on fuel as compared to air input. In the end, you must tune a burner back and forth between rich and lean to educate yourself on what constitutes the best flame from your burner; you can do this out in the open air, or in the equipment while it is warming up.

    You can also get thin yellow and red streaks in a perfectly tuned burner's flame, due to breakdown products of oxidation from some alloys of stainless steel, mild steel, or cast iron in flame retention nozzles. Flame nozzles of #304 stainless can put on quite a show that way; it's harmless. #316 stainless nozzles make fewer streaks and last longer.

Fuel rich (AKA reducing) flames, range from the faintest tinge of green in a blue primary flame envelope (AKA flame front) to bluish green flames that are pushing so much none combusted fuel into your shop's atmosphere that you feel like gagging. If the burner’s choke is completely closed the burner will make a lazy yellow flame like burning wood.

Neutral flames range from light to medium blue; they are neutral throughout this tint range for all practical purposes; what that means is, although their combustion chemistry is changing, you can't appreciate the difference without calibrated instruments.

    So how can you know when the blue leads the neutral range and inters oxidizing? The answer is that you can’t without a fair amount of practice. Eventually, you will learn to compare the flames from your burner at one time and another, so as to tune it perfectly.

Oxidizing (AKA lean) flames start just beyond medium blue, go through dark blue, and can extend into purple, if your burner is stable enough to sustain such a flame. While learning to discern the boundary between neutral and oxidizing flames, it is helpful to use small pieces of fresh ground steel in the forge, how fast and how much scale accumulates, gives you a faithful comparison; so can a watch, as oxidizing flames aren’t as hot as neutral flames.

    Flame color isn't the only sign of how well your burner is doing. The amount of secondary flame is also an important indicator; the less secondary flame the better. There is such a thing as perfect performance, which includes no secondary flame. Perfection is often the enemy of practicality. A small wisp of secondary flame is often better than no secondary flame at all; this is because air/fuel flames fluctuate more than oxy-fuel flames, so the "perfect" flame is likely to be slightly oxidizing part of the time. Since that wisp of secondary flame will burn up completely in the forge or furnace, it is better than added scaling of work pieces during heating, or oxidative damage to super-heated crucibles in a casting furnace. It should go without saying that tertiary flames indicate poor burner construction, or a very bad job of tuning.

    So, what is the practical upper limit for secondary flame? Is there flame coming out of the exhaust opening? Then your burner is either tuned to rich, or its gas pressure is turned up to high.

[Skidpad13]

Good evening everyone. I've scoured the thread as much as my eyes can bear. Likewise, I've been re-reading Mikey's book over and over. I have picked up that there have been some modifications to the original designs as presented in the original book. Some of the modifications I have been able to find are: (A) change the number of intake openings to an odd number in order to reduce cross currents, (B) ensure that the length of the burner mixing tube is between 8-9 times the diameter of the tube and (C) there may be some builds that benefit from a smaller orifice opening than the .035 tapered contact tip. 

So, with these specifications in hand, I've documented the most current version of the design as best I can assemble it in my mind. Since my day job is as an architect, I couldn't help but to lay this out in the computer first where it costs less and saves time to make changes.

If this entire exercise has already been completed and I just missed it please disregard this post and kindly direct me where to look as I have been unable to find this despite many searches and pages upon pages of reading.

I would greatly welcome everyone's input, especially that of Mikey if you would be so kind. Although I know, especially from recent posts, that each build is slightly different and tuning and modifications will be necessary for each one, I still want to start off on the best foot if possible and then tune the build.

One of the questions that I think I know the answer to I will state here for clarity: in optimal recommended configuration, where should the forward (gas discharge) end of the contact tip be in relation to the intake openings? Should it be in line with the forward edge, set back some distance? This is the one dimension that I feel is somewhat nebulous in what I have been able to find so far. This will drive the length of the accelerator tube connected behind the contact tip.

In relation to this, does everyone find that forward/rearward adjustment of the accelerator tube in relation to the bell reducer, is essential? If so, my thought to solve this is to drill out the threads in the bell reducer and  allow the 1/8" pipe nipple to move freely forward and back with three set screws providing both a locking mechanism for this as well as providing aiming screws for the centrality of the accelerator within the burner body.

Please use the attached images, especially the section view with callouts and notes, to document my understanding of the latest generation as well as for edits, comments, corrections, etc... the axonometric view and the exploded view are just to show any 3D context that the section view may leave out.

This and possibly a twin, will be used in a soon to be constructed forge. As many posts have suggested I am going to go and visit a local guru to see their setup before I begin on ours. I'm only a couple of hours from Wayne Coe as we are here in Nashville so I hope to visit him in the next couple of weeks and see his forge(s) before beginning to build ours.

Thanks for any comments or advice, corrections, etc... I'm always humbled by the amount of wisdom and patience from the members of this forum.

SF

Paul

[Mikey98118]

Paul,

As an architect, I think you are use to keeping the overall picture in mind, while dealing strictly with details. So, I will try to answer both the hows and the whys in that same manner. Since you have gone to so much trouble to include detailed drawings, I will go over them so that anyone willing to concentrate on them can get the maximum good out of the effort. Therefore, please keep in mind that I am speaking to a possibly wider audience, when answering your questions; my answer will be interspersed with them, so I will be using bold type for clarity.

Good evening everyone. I've scoured the thread as much as my eyes can bear. Likewise, I've been re-reading Mikey's book over and over. I have picked up that there have been some modifications to the original designs as presented in the original book. Some of the modifications I have been able to find are: (A) change the number of intake openings to an odd number in order to reduce cross currents, (B) ensure that the length of the burner mixing tube is between 8-9 times the diameter of the tube and (C) there may be some builds that benefit from a smaller orifice opening than the .035 tapered contact tip.

My preference for odd , rather than even numbers of air intakes to reduce the possibility of cross currents are stated in the book, but since publication I have further refined that to three intakes on all burner sizes; this gives the maximum benefit, spin wise, while leaving the widest possible ribs between air intakes, no matter what size burner is being constructed.

So, with these specifications in hand, I've documented the most current version of the design as best I can assemble it in my mind. Since my day job is as an architect, I couldn't help but to lay this out in the computer first where it costs less and saves time to make changes.

Another change is the choke sleeve; I have dropped the outward taper at its rear, which was overkill, and reduced its ability to modify burner performance. The loss will not be missed

If this entire exercise has already been completed and I just missed it please disregard this post and kindly direct me where to look as I have been unable to find this despite many searches and pages upon pages of reading.

No, you didn't miss anything. For several years I was unable to post burner drawings because of contract limitations. While that is no longer true, I am also no longer interested in these old burner designs, and so have made no new drawings,

I would greatly welcome everyone's input, especially that of Mikey if you would be so kind. Although I know, especially from recent posts, that each build is slightly different and tuning and modifications will be necessary for each one, I still want to start off on the best foot if possible and then tune the build.

One of the questions that I think I know the answer to I will state here for clarity: in optimal recommended configuration, where should the forward (gas discharge) end of the contact tip be in relation to the intake openings? Should it be in line with the forward edge, set back some distance? This is the one dimension that I feel is somewhat nebulous in what I have been able to find so far. This will drive the length of the accelerator tube connected behind the contact tip.

The tip of the MIG tip has worked out to work best when it is kept 1/4" to 3/8" back from the forward edges of the air intakes. So, why the variance? There were many different burner sizes in the book.

In relation to this, does everyone find that forward/rearward adjustment of the accelerator tube in relation to the bell reducer, is essential? If so, my thought to solve this is to drill out the threads in the bell reducer and  allow the 1/8" pipe nipple to move freely forward and back with three set screws providing both a locking mechanism for this as well as providing aiming screws for the centrality of the accelerator within the burner body.

Exactly right.

Please use the attached images, especially the section view with callouts and notes, to document my understanding of the latest generation as well as for edits, comments, corrections, etc... the axonometric view and the exploded view are just to show any 3D context that the section view may leave out.

This and possibly a twin, will be used in a soon to be constructed forge. As many posts have suggested I am going to go and visit a local guru to see their setup before I begin on ours. I'm only a couple of hours from Wayne Coe as we are here in Nashville so I hope to visit him in the next couple of weeks and see his forge(s) before beginning to build ours.

Thanks for any comments or advice, corrections, etc... I'm always humbled by the amount of wisdom and patience from the members of this forum.

I like your drawings. Just two things more; mixing tube length (the area beyond the forward edge of the air entrances) are subject to the "nine times" rule of thumb, which states that the ideal mixing tube length is nine times the inside diameter of any giving burner; shorter than that and the flame becomes shortened and less stable. Longer than that and the flame starts to lose potency.

Also you have combined my step nozzles with tared nozzles. The spacer ring in my flame retention nozzle design replaces that tapering you show in the outer tube.

 

It was fun interacting with you. Please don't hesitate to ask any further question you have.

Mikey

[Skidpad13]

Mikey, thank you so much for these clarifications! I apologize for missing your comments in the book re: odd-numbered intake openings, I'll be more diligent going forward.

I understand now that the step ring serves to give the enlarged opening for gas speed reduction so the taper in the SS nozzle end is no longer required. I'll eliminate that from the build.

I had intended to also ask about the one thing you have already clarified, the burner tube length. I want to further clarify this for my all-too-linear mind. In the attached image, should the length of the tube, at 9x inner diameter, be measured from the outer end of the nozzle (red arrow) or from the tube end where the expansion/step ring allows for gas/air mixture expansion (blue arrow)?

Finally, I truly appreciate your attention to this older design. I've read many posts so I'm guessing that the design currently taking the fore is the ribbon burner? I'm going to follow a similar documentation procedure for Frosty's NARB but I want to go see Wayne's forced air clamshell version before I go down that road. 

Cheers!

-Paul

[Another FrankenBurner]

9 hours ago, Mikey98118 said:

I am also no longer interested in these old burner designs

What are you interested in now?

[Mikey98118]

Updated designs, and two new burner designs; also updated forge designs. However, none of the changes sunset this burner series; they are just different; basically allowing people more choices in how they choose to build a burner. If you're after a hotter burner, you must look in the 3D printer thread. I firmly believe AFD is on to something important with his design.

[Frosty]

Sidpad: Mike forgot to answer your last question so I'll intervene. Blue arrow for mixing tube length. Not the flare end. 

Do NOT apologize for your questions, they are well thought, cogent and come with excellent mechanical drawings!

Good questions are a treasure, thank you!

Frosty The Lucky.

[Mikey98118]

2 hours ago, Skidpad13 said:

I apologize for missing your comments in the book re: odd-numbered intake openings, I'll be more diligent going forward.

My own family couldn't read that book; just too dry .

No, problem. If you read dedication, and then look at what art students are reduced to building with, it becomes easy to understand who and why the book was written to. Desperate people have excellent attention spans. I ran into a group of them at the Kentucky conference in 2004 (it was held at a university). Their hunger for real answers was all the reassurance an author could want

The nine times rule is the length of the mixing area; in other words, to the end of the mixing tube.

Ribbon burners are concerned with the nozzle area, or in their case, the burner block. The rest of the burner can be any design that serves.

16 minutes ago, Frosty said:

Sidpad: Mike forgot to answer your last question so I'll intervene. Blue arrow for mixing tube length. Not the flare end. 

Do NOT apologize for your questions, they are well thought, cogent and come with excellent mechanical drawings!

Good questions are a treasure, thank you!

Frosty The Lucky

Yeah; what he said

[Skidpad13]

Thanks to everyone for your excellent clarifications & detail.

That being said, my head is now exploding with the 3D thread (so thanks for that, ha). My son and I built a Prusa i3 with a 12"x12"x12" build volume back in 2014. I haven't run it in a few years as it started developing a nasty habit of going out of level during bigger prints.

So, we're still going to build the burner in the drawings above to finish what we started. However, expect to see me lurking with questions about the new tech. Holy cats, I mean seriously! 3D flexibility combined with high-temp ceramics for parts?

I have Colin Peck's book on waste oil furnaces that I was going to open up later this year. Now that I see the possibilities of ceramic & metal casting I'm losing my mind. This all feeds my creation  addiction way too much. It's similar to when I was deep into homebrewing. I couldn't tell which I preferred more; making the beer or drinking the beer. I know that I have problems and I promise to see a specialist about it very soon.

Thanks everyone!

Out of curiosity, has anyone used a computational fluid dynamics (CFD) modeling program to prototype expected mixing flows in the 3D nozzles? I apologize for asking this question completely blind since I haven't had a chance to read through the whole thread.  I just thought I'd ask since I have some experience with CFX4 from work I did some years ago. I can't wait to dive down this newly discovered rabbit hole...

[twigg]

I haven't heard of anyone doing CFD on these forums and I've only done about 100 hours of that torture in past jobs, but I have spent too much time pointlessly thinking about modeling a burner. You may already know this, but I'd just say: don't just throw a k-epsilon model at the wall and expect it to stick. Read about the "round jet anomaly" first. I am told there are solutions to this problem using Lagrangian methods (Stephen Pope's book "Turbulent Flow"), but I haven't gotten around to reading about it. Then you'd have to adapt those methods for the case of two fluids at different densities. You may even have to adapt it to account for the compressibility of the propane flow in the accelerating orifice! YIKES!

Edit: I should have lead with this, but the point is that CFD is just too darn hard to justify using it when there are so many smart folks with experience around here. Even if you didn't have their advice, you'd still be better off just guessing and testing prototypes than direct numerical simulation. The only good reason to invest the time is for personal satisfaction, and that I can relate to

[Skidpad13]

Twigg, you're wise words ring true. Architects know a little bit about too many things. It usually ends with me diving into a subject and emerging a few months later with a deep respect for those who've been doing it a long time.

The thought had flashed by as I was finishing that last post and my brain said "squirrel!" so I tacked it onto the end without the normal amount of consideration I'd give.

I'm going to spend a good amount of time reading & listening on this new-to-me subject. Then I'll draw up what I think I understand and see how that works. There are lots of incredibly smart folks on here and I have no problem following in the path someone else has already worked to clear.

[Mikey98118]

26 minutes ago, Skidpad13 said:

I know that I have problems and I promise to see a specialist about it very soon.

You are already seeing a team of specilists. We promis to do everything we can to deepen and widen them

3 hours ago, Skidpad13 said:

just thought I'd ask since I have some experience with CFX4 from work I did some years ago. I can't wait to dive down this newly discovered rabbit hole...

Don't forget to introduce yourself, and converse with with AFD. I really like him, but am a total dummy at computers, so that rabbit hole is lost to me. Frosty can at least speak his lingo

[Frosty]

k-epsilon? Are we talking about the 11th planet of Epsilon Eridani and I missed the segue? Is k-epsilon in the life zone? 

If you look in the right place your CFD software is available I'm sure. The type of induction machine we use for NA burners has been around for centuries, probably millennia though not as burners till brown gas started putting gas: ranges, furnaces, lights, etc. in the common presence. Modern versions are used for some pretty sophisticated things commercially and I'm pretty sure they don't do it by crude experimentation. 

I couldn't make the 1:12 ratio work when I started tinkering with NARB and changed to wood test blocks to find the balance of fuel air flow at the outlets.

I slam the flow into the plenum at a 90 to the direction of the outlets to more evenly distribute the flow without incurring the silly too high back pressure of the diffusion plates seen in the published gun ribbon burner. 

I tinkered one together just to prove to myself a ribbon burner does NOT require high static pressure air delivery. A T burner doesn't produce high static pressure, it barely blows the burning paper out of the forge when you light it. 

Lots of people have made some REALLY NICE versions and more than a few have used the commercial multiple outlet burners available for sale all over the world. Bet they do CDF calcs. 

I've been waiting till someone comes up with something to make the burner block from that doesn't get hot enough to pre-ignite the flow. One not requiring drilling holes, more than 100 in a few IFI home builds, would be a plus. 

How about 3D print burner blocks from Zirconia? The block could be 1/4" thick and have cooling vanes on the plenum side to keep it cool. 

There's a world of coolness happening out there right now. I mostly watch and read while keeping my jaw from hanging open till it aches.

 Frosty The Lucky.

[twigg]

Was extraterrestial life the key to the perfect induction burner all along? Who knew!

Frosty has a really good point: there are definitely experts out there who have done the hardcore math on induction burners. Contacting them would be the right way to get into CFD. I'm going to revise my words of caution: there is a lot of simulation software out there (COMSOL in particular) that gets marketed as being a one-size-fits-all solution to all your fluid flow mysteries. These software simulations tend to use approximate math that works 80% of the time ("k-epsilon" being the most common method). However, these methods are terribly inaccurate when round jets are involved (like the accelerating orifice in a jet ejector burner like Mikey's). The experts probably have a special vintage of secret sauce for this.

[Mikey98118]

Anytime the experts want to say something useful, they are welcome to take my place. There are loads of other things I could be working on. Meantime I won't hold my breath while, waiting, and waiting, and...