I’m trying to find out what purpose this type of design serves and how they are designed but have hit a wall with knowing what to even look for.
This piece of the voron stealthburner is the only example I can think of off the top of my head but I have seen them before in some sort of fan duct or funnel thing.
Started out ducting various things to other things such as fan to radiator, computer exhaust to outside, or to hanging wet clothes, etc. Then I got rabbit holed into research on different types of fans and how blades and rpm and fan dimensions change various things. A few prints and some purchased fan gadgets had the cone and blades thing and not knowing the names of them has made research difficult. My photo is a hotend heatsink+fan mount and probably the smallest example of this concept I have seen.
Most of the things I am thinking of making would originally performance first but if sound can be reduced by a measurable amount it would be worth testing.
Ah. So yeah like the other person said those static blades are stators. I havent found a good name for the cone aside from “aft cone” but that’s more for turbines. The stators should help it make pressure (that’s what they do in turbines) but the only reason I see for the aft cone is reduction of turbulence and since this is for cooling the hot end turbulence is actually a positive thing because it reduces the skin of hot air that sits against the heatsink fins.
If you’re pusing enough air you may benefit from a nose cone but it should probably be more hemispherical. Also an intake cone that’s like a trumpet bell might be beneficial.
For noise, most is probably in the blades but you may see some reduction by adding a sweep to your stators and/or adding a jaged pattern in some places like all the new jet engines do. Like this: https://www.nasa.gov/wp-content/uploads/2015/03/qtd2_sunrise_3024x2016_0.jpg
Granted, on the scale we’re talking here all of this will be splitting hairs.