Spiral hot air gun nozzles

[bitwelder]

Usually the hot air gun nozzles are straight, that is the end part of the nozzle is just a straight pipe (i.e. you can see through its hole)

However, I've seen some nozzles that on the inside have kind of 'spiral', so the blowing air at the center of the nozzle instead of exiting directly through the pipe would probably start 'whirling' around before passing to the exit pipe.

Are those nozzles useful, and in which situation?

[thm_w]

The end of the hot air nozzle should not be open, it should have a mesh or spiral pattern there already. This is probably enough to mix up the air to make it relatively even temperature.

Link or photo would help.

[coppercone2]

this is a feature on torches as well, seemingly backed by the HVAC industry

[bitwelder]

Link or photo would help.

I wasn't able to find any photo online that show the 'spiral', but anyway this is the type of product:
https://www.aliexpress.com/i/1005001407607925.html
Later I'll take some photos of the nozzles I have and post them here.

Edit: added photos from a 10 mm spiral nozzle seen from the inside (i.e. where it plugs to the hot gun) and the outside (the end pipe)

[S. Petrukhin]

Twisting the air flow allows you to slightly condense it, focus it, and reduce the divergence to the sides. If you look at the just the chinese air termfen for soldering, you will see something similar to the impeller, a swirl flow.