DIY Static mixer

[Frosty]

You can't mix them too much, it's not like they'll turn to butter or something. The trick is to find the point of diminishing returns where increased drag exceeds the value the flame improvements. 

( Shhhhhh, I'm being Cagey here Mike. The more folk wanting to prove us wrong the more likely we'll see something really sweet come down the pike and not have to do the work ourselves.) You are aware I can unscrew the T inducer off the NARB Plenum by hand, I don't even need a wrench. Right? I can adapt and adopt a cool mixer thingy fast and easy. Two of my favorite kinds of improvements you know. 

Frosty The Lucky.

[AdamTheSaint]

Right you are Frosty. I can't ever seem to leave well enough alone, which is why my old Harley chopper spends as much time on the lift as it does the road, if not more.

 

The huffing is the friction I was worried about undoubtedly, slowing the stream down. That was with solid "baffles" no?

 

Wonder what would happen with, say, a fine metal kitchen strainer cut and shaped into a spiral that fit inside the mixing tube?

[JHCC]

Yes, as you see. Very irregular, too. If you look at the animation above, the gas particles are represented as moving very regularly and smoothly. I suspect that this attempt’s irregularity created a lot of turbulence in the tube that did a good job mixing up the gas, but at the cost of increasing friction. 

[ThomasPowers]

As it is an animation you could portray the gas molecules any way the animator wanted.

[JHCC]

Fair point. Especially when the animator is trying to sell something. 

[Frosty]

Not a thing wrong with tinkering around no matter how well a thing is working right now. I wouldn't have lucked into a working NARB if I wasn't willing to tinker and accept the high probability my idea wasn't going to work and bull ahead anyway. It just worked with a little tweaking. It was a lucky thing and I'll take it. 

About that animation. It's cool but everybody needs to bear something in mind. The animator is ASSUMING particles actually behave THAT WAY.

I think there's a good chance they do behave that way but that's an assumption on my part. It's an animated model and probably holds true with a physical model say, clear plastic and smoke or colored water. To A DEGREE.

No matter, they're still MODELS not working devices. That's why we draw pictures, bounce ideas off each other, make models then prototype and test in the real world.

It's all part of the process.

Right now we're brainstorming static mixers in HOME MADE devices. AKA SkyBalling.

Skyball on Brothers. This is Fun Stuff. 

Frosty The Lucky.

[Mikey98118]

I don't think the NARB flames need much more than they have now; a little more mixing, with a little positive pressure from a computer fan, maybe. But a little more NARB performance could be a BIG old deal; ya never know

[Another FrankenBurner]

I like the idea.  I think in a blown system, it may be quite useful in mixing.  In an atmospheric burner, I suspect it will cost too much.  No free lunch.    By this I mean that you may get better mixing at a cost of induction air volume.  This may be able to be countered by dropping jet size but then you have to accept a drop in output.  If your burner has a problem with mixing, it may be a worthy trade.  Inducing all the air in the world means nothing if you don't mix it well.

This device creates a reverse of flow rotation, several times.  This has to increase the resistance.  Even the animation shows flows crashing into each other, that is how it works.

My experiments have had the goal of mixing the FAM well and inducing as much air as possible.  This has required never directly impeding it's flow path.  Any time I did, it reduced induction.  

I can't speak much on the NARB's, as I am just now tinkering with them, but I imagine Frosty has it right in that there is so much turbulence that mixing is happening.  All of my NARB experiments currently are geared towards reducing this turbulence as much as possible so that more air can be induced, with the end goal of the cleanest flamelets.

As Frosty said, tinkering is worth doing.  Sometimes there is nothing better then being wrong.  I will be building a few of these mixers in a similar fashion to JHCC except that I will be cutting the strip from both sides for the reverse twisting.  I have an idea on a twisting jig.  I will put them into a few burners to see what happens. 

[Buzzkill]

I'm thinking about stretching out a length of spring and inserting it into the mixing tube to see what, if any, effect that will have on my NARB.   I think of it as raised rifling.  I'm hoping it will produce some additional swirl in the mixing tube.  If I get time this weekend I'll give it a shot.

[JHCC]

I wonder if the temperature inside the tube is low enough to make something from aluminum sheet from a soda can....

[Frosty]

If your mixing tube is hitting 100 f. you're doing it wrong. Al shouldn't be a problem unless chimney effect cooks it hard when you shut down.

A thought I had years ago was to extend a long pin from the T and put a little shallow pitched, pinwheel propeller on it. I just wanted it to stir the flow, not impede it so I figured I'd start with blades almost parallel with the tube pitched just enough to spin. It couldn't be centered of course, the jet has that honor though a bit of tweaking could put it on center but . . . ? I never experimented so it's just an idea. 

Any takers? 

Frosty The Lucky.

[Mikey98118]

I think another good idea is bubbling away on the stove...

[Frosty]

<SHHHHH!> I'm waiting for a nibble Mike! You keep this up you'll spoil my cagey. 

What obvious thing do you see wrong? I've considered a number of fixes but as suggested. . . Bwa hahaha!

Frosty The Lucky.

[Mikey98118]

That's just it; I don't see anything wrong--just a whole lot of right thinking

All ribbon burners need is a couple more tweaks to got from very good to amazing.

 

That should read "get" not got...time for more coffee.

[Frosty]

I was referring to the pinwheel mixer, not all these guys jumping in to the game. I'm all for new ideas and experiments.

My next NARB series will begin with coffee stirrers and a much thinner block. I'm probably going to have to buy better lumber for tests though. <sigh>

Frosty The Lucky.

[jwmelvin]

2 hours ago, Frosty said:

My next NARB series will begin with coffee stirrers and a much thinner block.

What are you going for as the aspect ratio of the outlets? I imagine that is how one would pick the thickness of the block. With a forced burner, a long outlet would create a resistance, and that would help create a uniform distribution across the outlets. But with NA, it may be better to focus on plenum design and use a relatively thin and therefore low-resistance block. 

[Frosty]

Too much math. I make models in wood and adjust outlet numbers to reach optimum flow. The wood test blocks last about 30 seconds before degrading to the point I can't read the flame usefully. I can tell what I need pretty quickly, light it up and run it up and down the regulator range and observe flame shape and stability. 

I'm not so good at math but know when I'm out of my depth. The thickness of the block is only one of a number of factors. Diameter of the outlets being most significant as resistance changes with the square of the change in diameter. Then there is the material the burner block's made from. 

The effect of thickness I want to check is how much length I need to create a laminar flow for a good flame profile. I want to keep the block as thin as possible to enhance cooling so the rate of propagation doesn't exceed the flow velocity.

If I started trying to calculate this stuff I'd have to take some math courses. I experiment instead, I'm good at that. 

Frosty The Lucky.

[Dr.X]

Any updates on this?

[Frosty]

I haven't done more experimenting but lots of guys here on Iforge have really surpassed what I did.

NARB lives is one thread IIRC.

Frosty The Lucky.

[swedefiddle]

Dr. X,

Malcolm, I Presume?

Neil