3D printed plastic burner experiments (photo heavy)

[D.Rotblatt]

2 hours ago, Another FrankenBurner said:

I don't believe the curve has anything to do with the measurements of the pitot tube aside from preventing turbulence at the ports

You’re probably right. I guarantee it’s well studied. 

DanR

[Frosty]

G. Venturi published his principle 15 years after Bernoulli died. In every description a quick search hit, the Venturi effect is described as a specific example of the Bernoulli effect in a constricted tube. Venturi's paper is regarding the application of the low pressure zone to draw liquid or gas into the accelerated flow. 

What I remember clearly is how hard Bernoulli and his family fought Venturi as a thief for usurping Bernoulli's principles for money. It wasn't until Bernoulli couldn't testify in court that Venturi was able to publish. 

Anyway. I misspoke when I said the Venturi effect isn't in operation in NA burners, especially wasp waisted burners, it is. It's just not what makes them work, it only makes them work better. 

I need to think about how much I've allowed myself to become invested in shady tricks done more than 200 years ago and stop taking issue with such a minor thing. 

Agreed, Venturi himself would look at a pitot tube and say I was wrong. However, it operates under exactly the same physics, as do airplane wings and propellers.  The diagram I posted is JUST a diagram, not a working pitot tube, don't look at it and think it is.

Frosty The Lucky.

[Mikey98118]

We see and agree to your point. However this burner style are commonly called venturi burners. If we are going to "swim against the tide" we need as handy a title to supplant that with...

[D.Rotblatt]

6 hours ago, Mikey98118 said:

we need as handy a title to supplant that with...

Frosty has been using "Naturally aspirated burner" for his ribbon burners - that works for me.  They're called that on Ron Reils old site too.  I use that and Venturi interchangeably.

DanR

[Another FrankenBurner]

I had picked up on disdain for Venturi.  Now I understand.  Thank you for the information.  It is disheartening that history is filled with so many examples of trading integrity for notoriety and a pay check.  

At least you can't really know about Venturi without knowing about Bernoulli.  To use a Venturi flow meter, you have to use Bernoulli's equation.  Not every Bernoulli is a Venturi but every Venturi is a Bernoulli, kind of thing.

I think I understand what you are meaning with the mechanics.  You are saying that the same dynamics which entrain air in a burner without a constriction(e.g. a Mikey) are also responsible for some of the air entrained in a constricting burner?  

For nomenclature, Venturi burner is an industry term.  So is naturally aspirated, which is interchangeable with atmospheric, but this describes any burner which isn't blown/gun/powered/forced air and is not a description of constricting burners vs straight burners.  I recently found the term inspirator but it also describes the naturally aspirated device which could be constricting or not.

We can use the term waisted in lieu of Venturi, but it opens the door to "My burner is so waisted that it can't work." 

[D.Rotblatt]

37 minutes ago, Another FrankenBurner said:

description of constricting burners vs straight burners

NA straight burner and NA constricting burner???

[Another FrankenBurner]

I was meaning that the term naturally aspirated does not describe the shape of the burner tube.  It simply means it does not have a powered air supply.

Mikey burners are a straight burner because they have no reducer.   Reil burners are constricting.  The inlet constricts to the mix tube. 

Add the tapered outlet and you have what looks like a Venturi tube.  They use the terms convergent section, throat, and divergent section when talking about Venturi tubes.

[Mikey98118]

Which is why I started calling them wasp-waist burners as the only other description I could come up with from the Net. Unfortunately, a simple catchy name like "venturi burner" is hard to cancel out

[pnut]

What about just calling it a wasp burner. Sounds catchy to me. Maybe a naturally entrained air burner or NEAB for short.

Pnut

Edited September 25, 2019 by pnut

[Another FrankenBurner]

Brick House burner 

[Mikey98118]

Perhaps 'divergent" burner might get the point across best?

[G-son]

Wasp waist DOES sound good, and mentioning the waist makes it pretty clear they have one. Sometimes being "more technically correct" doesn't help people understand what you mean, quite the opposite when you start using words most people don't use regularly and perhaps don't even know what they mean.

[Frosty]

15 hours ago, Another FrankenBurner said:

Not every Bernoulli is a Venturi but every Venturi is a Bernoulli, kind of thing.

Ayup. 

15 hours ago, Another FrankenBurner said:

I think I understand what you are meaning with the mechanics.  You are saying that the same dynamics which entrain air in a burner without a constriction(e.g. a Mikey) are also responsible for some of the air entrained in a constricting burner?  

Not quite. I'm saying a Venturi is NOT a driving factor it enhances performance. The jet "entrainment, induction, etc." dynamics are responsible for ALL the entrained flow. NA burners will work just fine without a Venturi. It's a feature, not the definition. Having a turbo charged engine doesn't mean you drive a turbo charger. A turbo doesn't make the engine work it makes it work better. Make sense?

I like the term "inspirator" from the Latin, "a thing that breaths in," synonymous with Aspirator". The root being "inspire" the breath of life, source of the word "spirit." Inspire is to breath spirit into someone and to expire is to breath your last. Aspire is to breath in life, also known as ambition.

Like etymology, ME? Nahhhh. My love of etymology too often gets me in discussions like this one. I feel words should mean what they mean: "spirit and letter," unfortunately they diverge quickly in a living language so delving into what something meant when it was made up is more of a hobby. I lose track of that and find myself arguing semantics and I hate arguing semantics. 

Unless it's just for funsies how about we just leave folk to call NA burners what they do. Venturi is just a button for me, one I need to forget about unless it actually means something at the time. 

For instance. The flaring outlet is described and quantified by Bernoulli in one of his principles but has nothing to do with a constriction as in a venturi. This is one of Bernoulli's I actually understood as he described it. (No, not in Italian!) This one is really intuitive and goes like this. A moving fluid entering a larger volume must lose pressure or velocity. There was more but the same amount of material has to expand to fill a larger volume and so loses pressure, expressed by PSI or velocity.

Bernoulli also described effects on a fluid flowing into an expanding volume in incredible detail. The one principle I quote often is the max 1:12 taper rule.  Increasing or decreasing the cross section of a flow more than once every twelve times the cross section causes disrupting turbulence. Becomes non-laminar. The impression I got was he was a LOT more interested in describing turbulence in all it's forms than the effects of laminar fluidics. Linear burners were in common use in Bernoulli's day and I don't think I saw anything by him regarding burners. They probably bored him.

Frosty The Lucky.

[Mikey98118]

Guess I"'ll stick with "wasp-waist," until someone comes up with a catchy description

[Another FrankenBurner]

We have been testing the 3D printer nozzles as jet orifices.  I had one which performed much worse than expected.  I connected it to water:

Hmm.  We were a little quick with the assembly of this one.  More care with alignment.  Since I had the water rigged up, I checked several tips.  Most of them were great.  I had a generic mig tip which the tip itself was aligned but the jet veered off.  

As to the printer nozzles as orifices, the 0.8 mm and the 023 mig tip are similar bore.  When connected to water, the printer nozzle stream jets out twice as far as the comparable mig tip.  When put into the 3/8" burner, the flame is shorter and has a roar.  It looks very good.  I like it.

I am going to try the 1 mm in the 1/2" burner next.  I think I will have to drill out the 1 mm to larger sizes to find a good match for the 3/4" burner.  You can get a few larger sizes but they are not common and the range of sizes falls off.  

 

[bertie_bassett]

That looks like a burr or dent on the end of the nozzle orifice to me. i cant see any other reason for the jet to go askew like that.

my 3/4 burner has a stable flame with only a 0.8mm nozzle, although it hasnt been tuned yet so bigger might be better.

[Another FrankenBurner]

There is no dent or burr.  I was excited about playing and made the connection too quickly/sloppy.  The printer nozzle was brazed in at a small angle.  

I am a full convert.  3D printer nozzles over the mig tips.  Working with brass instead of copper is great.  These induce more air per orifice diameter.  I suspect they are putting out more fuel as well. 

Thanks for the suggestion G-son.

We made up several new tips with the 0.4mm, 0.5mm, 0.6mm, 0.8mm, and 1mm 3D printer tips.  We drilled out a few to 0.043", 0.046" and 0.052".  We have quite an assortment to play with now.

The 3/8" burner does well(in free air) with the 0.8mm and the 1mm.  It will be interesting to see what it does in a forge.  I suspect it will back down to the 0.8mm.

We ran the small forge for several hours while swapping out tips and leaving the pressure alone.  It has the 1/2" burner which originally had an 030 mig tip.  We tried the 0.8mm, 1mm, the drilled out 0.043" and 0.046".  We listened to the sound, inspected the main flame, monitored the dragons breath, and did some temperature measuring.  

The 1mm tip is hands down the winner.  No dragons breath, violent loudest roar, 100°F higher forge temperature.  At 5 psi we are running 2450°F in the forge.

It is interesting that the 1mm(0.0394") was the replacement for the 030 mig tip which measures at 0.039".  On that thought, we drilled one out to 0.052" to match the 045 mig tip in the foundry 3/4" burner.  This burner turned into a whole different dragon.  We are looking forward to the next pour for a real test of performance.

I am now planning a 1/4" burner which uses these.  Maybe a smaller burner, just because I have the tiny orifices to go with it.  

[G-son]

That looks really good! Promising for a small (hand held) burner using one of the smaller nozzles.

[bertie_bassett]

ahh i hadnt realised you had brazed the tip in, i had assumed you had screwed it in as i had. 

im thinking the smaller tips will work well in a tiny burner, if i get a chance ill try to draw someting up and get some opinions prior to machining anything.

next question is how will these nozzles work with a printed/cast inlet chamber? 

[Another FrankenBurner]

We are using these nozzles with a printed/cast inlet chamber.  In the image of the forge, you can see it.  Unless I am misunderstanding what you mean.

[D.Rotblatt]

Lookin awesome!  How big is the interior of your forge?

DanR

[Another FrankenBurner]

That is the "small" forge which is at 185 in³.  It has 1 inch of blanket and half inch of kast o lite.  The next will have 2 inches of blanket, 3/8 inch of kast o lite and a coat of plistix 900F.  

[Mikey98118]

On 9/29/2019 at 7:34 PM, Another FrankenBurner said:

I am a full convert.  3D printer nozzles over the mig tips.  Working with brass instead of copper is great.

Brass is better than copper. In the twenty years since I started using them for gas orifices on burners, MIG contact tips have become an expensive pain in the backside to employ too! 3D printer nozzles didn't exist back then, but they do now; they are also cheap and easy to squire

[Another FrankenBurner]

Now that I know the 1mm is measured running the forge hotter than the rest, I setup a burner in open air to take a good look at the flame.  I also took a look at the same burner with the mig tips I was running previously to see if I noticed a difference.

Previously I had run this burner with the 030 mig tip.  I forgot I had run it with the Miller 030 mig tip because it ran better than the generic.  The Millier is at 0.037" and the generic is at 0.039".  

With the 1mm(0.0394") printer nozzle, the flame is shorter and louder.  It is exactly what Mikey describes as a neutral flame.  A uniform light blue color.  

[D.Rotblatt]

12 hours ago, Another FrankenBurner said:

That is the "small" forge which is at 185 in³.

That's about the size of my NARB forge, a little smaller.  It's also running on a .036-.040 jet (depending on which burner I stick in it as an injector).  But 2450 at 5lbs is awesome!  Very efficient!  I bought a bunch of 3D printer nozzles last week, along with some drills to make different sizes.  It will be interesting to see how they work!  They are M6 threads, which should work with the schedule 80 1/8" pipe.  ID is .215 and max thread on M6 is .234...close but with some pipe dope it should seal (should use a .19 hole for m6, so it'll be loose).  I hope so, it would make it easy to test different sizes.