Saw this in one of my feeds. Pretty impressive results. Might need to give something like this a try on the GF…
Read this the other day and made a quick little insert version (laser cut of course!) for my Trotec nozzle. To the touch, the air does feel smoother coming out (but that’s kind of like a butt dynamometer, I bet). Didn’t notice any difference in cutting, but they’ve also extended the nozzle tip much closer to the material surface, I believe.
As far as improving, I’d be curious about the effects of a window after the lens (basically, integrating a window into the nozzle). That would probably get them where they want to be as far as truly directing the airflow without a large center bore opening for the beam (where a lot of the air is flowing through). Not sure how fast something like that would get dirty though, seeing as the lens (which sits higher up) still gets dirty even with the air flowing down and through. The air assist on that system is designed to create a type of “air curtain” around the optics to help keep them clean.
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Yeah. Arguably you’d want two high velocity flows. One directed at the lens to keep it clean, and another directed at the laser spot to keep it clean… doable. And while the article above talks about the great lengths the guy went to to get laminar flow, I’m wondering if it’s just the fact that the airflow speeds up as it’s choked down through the nozzle. Imagine if all the air coming off the GF assist fan were passing through a 1/4" diameter nozzle directed at where the laser hits the workpiece. The velocity of the air would be significantly higher. Laminar may not matter a lot or at all.
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Well shoot, I wish I still had that CFD software I pirated once, because daaaannnng, so many optimization opportunities here.
Nothin’ like a good science project! 
It’s already choked down. It has two different nozzles - one is 3mm (big hole nozzle) and the other is quite a bit smaller, 1.5mm maybe? All of that air is forced down and out through that orifice.
I won’t pretend to know much about the rest - as far as velocity, etc.
I also know nothing about laminar flow either. 
One thing that isn’t mentioned is how much air pressure they are running. I’ve heard of some people running 60-70-80 lbs of air and claim that it’s the bees knees. And I’ve also heard that it’s BS/no gain over just minimizing flaming.
Anyways, looking at the cross section, (the secret to clean laser cutting: Designing a better laser nozzle using 3D-printing – Nervous System blog), the “ports” only extend so far down into the nozzle. From there, it would be turbulent air, I think.
I run 20psi on the RedSail. More starts to disturb the material. Not sure even a Seklema mat would hold down paper or cloth in an 80psi windstorm 
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