Discharge cones and air inlet grills for axial fans

[80251]

These passive noise reduction devices are normally used in large industrial and agricultural applications but would they make a difference if used in PC's? There are also large custom made discharge cones for industrial fans that also act as mufflers (and look vaguely like straight through mufflers I've seen used on dirt bikes):

https://www.assemblymag.com/article...uction-options-for-axial-and-centrifugal-fans

 

[Toothless]

Good luck getting a bunch of those to fit your case. If you want quiet, buy better fans.

 

[Deleted member 205776]

Buying some silent fans helped out my ears a lot and would probably be way easier to do than this.

 

[80251]

I'd figure designing, marketing and selling plastic air inlet grills for standard 92mm, 120mm and 140mm fans wouldn't be too difficult. Ditto for the discharge cones.

 

[tabascosauz]

You......do realize how loud industrial fans are and why they might need those things? I used to assemble power distribution cabinets with lots of those fans, if you use them in a daily driver that sits next to you and not an OC bench then you should reconsider your choice in fans before you think about "discharge cones".

There's some merit to having a 3D printed inlet shroud for a downdraft CPU cooler or GPU heatsink in some ITX cases, but you haven't said anything about that application, and it certainly doesn't involve those other wacky devices either. I think @wolf has an example of such in his case

 

[80251]

But wouldn't the principles be the same for any axial fan? Outlet cones aren't designed to reduce noise (although that might be a fringe benefit). Outlet cones are designed to facilitate static regain making the fans work more efficiently.
Static regain is discussed on page 8:
https://content.greenheck.com/publi...003/VaneAxial_Application_Perf_Supplement.pdf

 

[oobymach]

No, in a pc case there is only so much room, most fans are flush mounted and can be silenced easily in bios. The addition of a sound suppressor would no doubt restrict air flow, be it more efficient or not.

Blade design on your fan is critical for your task, if looking head on at the fan you can't see between the blades the fan has high static pressure and low cfm (best for radiators), if you can see a lot of empty space between the blades the fan has low/medium static pressure and high cfm airflow (best for input/output on your case).

Fan specs usually have a noise output in decibels, 25 and up you're going to hear the fan, 20db and under will run much quieter, or just use bios and manually set fan speeds until you're happy.

 

[80251]

Did anyone actually bother to read the article? All the mechanisms discussed either decrease fan noise or increase fan performance or both. If anyone here want's to dispute the engineers at EBM-Papst and their findings please do so but back it up with proof.

 

[8BitZ80]

I don't dispute their findings, but applying the same concept on a PC fan is like wearing a full hazmat suit and respirator to clean the toilet seat. No law against it, but.....there are more productive ways to spend your time.

 

[claes]

I’d be interested — assuming you have a 3D printer or access to other tooling to test I’d be curious to see the results!

Most mass produced workstations include ducts but without a focus on fans. I could see this being especially useful in combination with a duct in multi-GPU setups where noisy axial fans are common.

 

[80251]

I don't dispute their findings, but applying the same concept on a PC fan is like wearing a full hazmat suit and respirator to clean the toilet seat. No law against it, but.....there are more productive ways to spend your time.

Huh? How do you know it wouldn't be productive? What if you could get the same perf. out of your fan(s) at a much lower RPM and noise signature?

 

[elghinnarisa]

Huh? How do you know it wouldn't be productive? What if you could get the same perf. out of your fan(s) at a much lower RPM and noise signature?

Probably because the article in question doesn't define anything specific. Just a comparison chart of noise levels. With what fan? at what RPM? how much air is it pushing? I mean if I can cut 9dB from a 80dB fan. Yeah thats cool. But it aint gonna be 9dB on a 17dB PC case fan, thats for sure.
Their source just states "appliance DESIGN " and I am way too lazy to find what specific document that is.

 

[Ferrum Master]

No one looks at plots...

If you look at the graphs it shows FAN noise on the realms of hammering something past 85dB also no working RPM's are stated.

I would agree that it can bend the noise at such jet like levels... the question is, where the energy ventures away? At such noises it can help bringing the noise from stupid loud to somewhat very loud. At PC usage scenarios it is useless.

 

[80251]

Probably because the article in question doesn't define anything specific. Just a comparison chart of noise levels. With what fan? at what RPM? how much air is it pushing? I mean if I can cut 9dB from a 80dB fan. Yeah thats cool. But it aint gonna be 9dB on a 17dB PC case fan, thats for sure.
Their source just states "appliance DESIGN " and I am way too lazy to find what specific document that is.

Here's the EBM-Papst document (that also has links to the products in question):
https://info.ebmpapst.us/ebm-papst/bid/183768/Fan-Noise-How-to-Control-Air-Turbulences

The conical output diffuser AxiTop states the following advantages:
'The greater efficiency allows you to reduce the speed, lowering the acoustic pressure by up to 7.2 dB(A)and energy consumption by up to 27 % with unchanged airflow'

All the HVAC literature I've read argues against free discharges for axial fans, why would PC axial fans be any different?

 

[8BitZ80]

Huh? How do you know it wouldn't be productive? What if you could get the same perf. out of your fan(s) at a much lower RPM and noise signature?

For a start, it's best to be aware that marketing material is NOT gospel. Far from it.

There's a few questions that need to be asked:

Has it been independently verified to work? Where are the research papers that test these technologies? Why do their white papers contain no technical information and are written by staff with the word "market" in their title? Why are other companies not making their own versions of this game-changing technology?

It's a case of being wrong until being proven right. They certainly do provide some tantalizing tidbits of information, but there's also quite a lot of details that are missing. @elghinnarisa seems to already be aware that it doesn't pass the sniff test.

Then you'd be taking those concepts and applying them to a completely different product on a much smaller scale.....it's incredibly unlikely that miracles will be happening at that point.

 

[elghinnarisa]

Here's the EBM-Papst document (that also has links to the products in question):
https://info.ebmpapst.us/ebm-papst/bid/183768/Fan-Noise-How-to-Control-Air-Turbulences

The conical output diffuser AxiTop states the following advantages:
'The greater efficiency allows you to reduce the speed, lowering the acoustic pressure by up to 7.2 dB(A)and energy consumption by up to 27 % with unchanged airflow'

All the HVAC literature I've read argues against free discharges for axial fans, why would PC axial fans be any different?

They are different because they are different products.

In the link you show they are using a 800mm industrial fan, that is floffing on up to 70dB+. Do you really think that a up to 20dB difference on a 800mm fan that normally screams around at 70dB+ will translate in to the same major improvement for a tiny little petite 140mm fan silently going by at 19dB? Because it isnt, and it won't.
I do not doubt it can help, not at all. But it will be a minuscule difference unless you have something very big or very loud, or both.
Also that link is also not a reference or a source. Its just... a article.

 

[Shrek]

For me the worst noise came from the video card fans, so I moved to fan-less video cards.

 

[80251]

For a start, it's best to be aware that marketing material is NOT gospel. Far from it.

There's a few questions that need to be asked:

Has it been independently verified to work? Where are the research papers that test these technologies? Why do their white papers contain no technical information and are written by staff with the word "market" in their title? Why are other companies not making their own versions of this game-changing technology?

It's a case of being wrong until being proven right. They certainly do provide some tantalizing tidbits of information, but there's also quite a lot of details that are missing. @elghinnarisa seems to already be aware that it doesn't pass the sniff test.

Then you'd be taking those concepts and applying them to a completely different product on a much smaller scale.....it's incredibly unlikely that miracles will be happening at that point.

Here's the science behind the use of output discharge cones on axial fans (page 5), with actual mathematics to prove its worth:
http://www.fluid-technology.com/wp/wp-content/uploads/Fiberglass-Axial-Flow-Fans.pdf

Wouldn't static regain be useful on heatsink finstacks or radiators?

 

[claes]

This forum is really negative... I don’t know how a 27% energy reduction translates to RPMs, but slower fan speeds are slower fan speeds.

The people responding here seem to be just trying to win points by making fun of you and ignoring your research... If you’re serious about this you’re best off building a prototype and seeing what happens.

I agree with your premise, as the research bares out. Whether or not the kind of gains your research shows will transfer to smaller components is another story. Maybe the haters are right, and it won’t, maybe they’re wrong and it will?

Sure, a 2dB decrease or whatever is nothing to write home about for the vast majority of PC builders, but for people who are anal about noise like I am, or are trying to shave 2* off of their components when benching with industrial fans at 3000rpm, it’s all the difference in the world and certainly with throwing a few bucks at.

I tried to do some research myself but couldn’t find much outside of datacenter cooling, but given that shrouds have proven so effective in workstations and servers I think it’s worth experimenting with. Hope you do!

 

[ZenZimZaliben]

Laminar Flow is a real thing, and very useful. You could easily 3d print these. I actually printed one for my 3dprinter for more pressure at same rpm and works well.

40mm, 30mm, & 80mm Fan Compressor Turbines by Br4ndosaurus

Sandwich this between your fan and mount for more concentrated and laminar airflow. This is about as aerodynamic as I could get it. The plate is 7mm thick and the cone is 20mm dia and protrudes another 13mm. The holes are 3mm. I printed one and it actually works well. One is adjusted for a...

www.thingiverse.com

 

[agentnathan009]

These kinds of air flow directing devices may help with PC axial fan issues, or, it may be that the airflow is to low and it won't be of much use. I'm a big fan (no pun intended) of blower type fans. However, in typical PC applications they are small and loud. but the small blower fan that I have in my computer room sends a strong stream of air across the room and it isn't too noisy, something an axial fan has trouble doing. I properly sized (herein lies the problem with using them inside PC cases) blower fan can move air like a jetstream, and can be quite useful for cooling PC components, but once you scale the size up to a more efficient level, then become impractical. Axial fans are thinner and a better fit for PC cooling equipment. Thus, any designs that can improve upon the drawbacks of axial fans (dead spot in center area of fan, low static pressure and low airflow when compared to blower type fans) are a win, especially if cost effective. Consider how much R&D went into Noctua's flagship fan, the NF-A12. This is a 120mm fan that can spin at 2,000 RPM and really isn't that loud for the RPM. It has good static pressure characteristics, noise, and airflow all combined into an expensive fan design ($30). I had a 120mm Arctic Cooling AIO (1st gen version) hooked up to a 2600X. At stock performance it kept CPU around 75c when working CPU. Merely replacing the pusher fan with Noctua NF-A12 the noise level went down a tad and it shaved off 4c.

 

[1freedude]

Somewhere i have a top of a plastic cereal bowl because i cut it off of the bowl to use as an intake shroud. Everytime I ate a bowl of cereal, all i could see was the intake of a fan. I never put it to use.

While I'm not a thermodynamisist, I do know that turbulent air will get rid of more heat than laminar air. Shrouds and cones make the flow smooth and laminar....the exact opposite of what air-cooled pc towers need.

For looks on a custom case, do it, but dont expect any performance games.

If you want to build and sell them, I would create a rigid mold to create many of them at one time. I have worked in an advanced composites shop as a mold creator and part maker. A 3d print may not be practical for volume production.

Regards, 1fd

 

[ZenZimZaliben]

While I'm not a thermodynamisist, I do know that turbulent air will get rid of more heat than laminar air. Shrouds and cones make the flow smooth and laminar....the exact opposite of what air-cooled pc towers need.

For case fans, yeah I agree. But for any fan blowing on a heatsink or radiators they improve performance a lot. Even for case fans the Inlet Shroud reduces blow back a lot.

 

[Shrek]

One thing I hate about a lot of power supplies is how part of the fan is often shrouded by being partly covered; not sure this is the best approach.

 

[WhitetailAni]

One thing I hate about a lot of power supplies is how part of the fan is often shrouded by being partly covered; not sure this is the best approach.

I opened up my Thermaltake TR2 600W to replace the fan (it was making horrible noises) and 90% of the fan was covered by a plastic sheet.
That got removed quick.