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 Post subject: Fan curves: I can make them
PostPosted: Fri Jan 14, 2011 7:22 am 
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Joined: Mon Apr 27, 2009 9:13 am
Posts: 59
Location: Canada
Hello I just thought everyone should know that I have a calibrated wind tunnel that I can use to make fan curves (which are curves plotting fans airflow output across different system backpressures).
I dont have any fans of note that are worth testing but at some point i plan to test some a slipstream, sflex and gentle typhoon.

I dont remember the accuracy of the airflow or pressure measurements but I believe it works quite well down to 2 cfm and ? inchesH20.

Reply to this or message me if you have anything in mind or fans you wish to send me to test. I can also test system response curves of heatsinks (which is where you see the pressure needed to blow X CFM through a heatsink).

--------------------------------------------
These are useful because it gives air flow (@ 0 back pressure AKA stated values in spec sheets) static pressure (@ 0 CFM) and everything in between which I can also take at various voltages (only 12-7-5 since they take some time). If a fan has low pressure @ 20 CFM then its airflow will probably drop to something like 10 CFM when blowing through a large heatsink. If you are trying to push air through a dense heatsink, you would look at something like the 2 inchesH20 mark and find the fan with the highest airflow, and best acoustics.

Attached is an example of how you know what the airflow of a system will be if you have a fan curve and system response curve.
Attachment:
operating point.JPG


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 Post subject: Re: Fan curves: I can make them
PostPosted: Sun Feb 06, 2011 5:24 pm 
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Joined: Thu Feb 04, 2010 6:06 pm
Posts: 3395
Location: US
chico1st wrote:
I dont remember the accuracy of the airflow or pressure measurements but I believe it works quite well down to 2 cfm and ? inchesH20


1. Accuracy on absolute measures isn't that important if you can compare fans using the same measure that is consistent and reproducible.

2. What you have done is very impressive. Please consider reposting this message here:
viewtopic.php?f=9&t=58350

3. Have you done any testing since you posted this message?

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 Post subject: Re: Fan curves: I can make them
PostPosted: Sun Feb 06, 2011 5:56 pm 
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Location: US
Have you seen this?

Some Really Nice Fan tests
viewtopic.php?f=9&t=61442

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"Aristotle calls man the rational animal. All my life I have been seeking evidence to confirm this" Bertrand Russell
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former" Albert Einstein


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 Post subject: Re: Fan curves: I can make them
PostPosted: Mon Feb 07, 2011 8:01 pm 
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Joined: Thu Feb 04, 2010 6:06 pm
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Location: US
How about a picture of your setup?

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"Aristotle calls man the rational animal. All my life I have been seeking evidence to confirm this" Bertrand Russell
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 Post subject: Re: Fan curves: I can make them
PostPosted: Tue Feb 15, 2011 7:29 pm 
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Joined: Mon Apr 27, 2009 9:13 am
Posts: 59
Location: Canada
sorry i didnt come to the forum for a while because the thread hadn't had any activity.

Quote:
How about a picture of your setup?

I cant post pictures as this is my setup at work. I'm allowed to use it for whatever but I doubt i can post pictures of the setup, work secrets i suppose.

Quote:
1. Accuracy on absolute measures isn't that important if you can compare fans using the same measure that is consistent and reproducible.

The test is very reproducible, its a professionally calibrated and serviced wind tunnel.

Quote:
Some Really Nice Fan tests
viewtopic.php?f=9&t=61442

The issue with this test, is that the fans are just blowing into some random tunnel/enclosure which doesnt have a known back-pressure. If he was blowing the air through a certain heatsink at least you would know the airflow through that heatsink.
At least that's what it looked like to me.
You get zero back pressure by having a fan on the exhaust of the tunnel and having 0 mm/H20 pressure in the middle of the tunnel.

Quote:
2. What you have done is very impressive. Please consider reposting this message here:
viewtopic.php?f=9&t=58350

Good idea, i will post there shortly.

Quote:
3. Have you done any testing since you posted this message?

I've done tests since then but I do them for work and few fans have looked worth testing. We use high-airflow high-pressure fans usually so I cant post anything you guys would be interested in. Although I tested one fan which had amazing airflow/pressure and 80 dBA! (We have an anechroic chamber but there is so much noise in the building it wont go below 30 dBA).


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 Post subject: Re: Fan curves: I can make them
PostPosted: Mon Feb 21, 2011 6:43 am 
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Joined: Thu Feb 04, 2010 6:06 pm
Posts: 3395
Location: US
chico1st wrote:
Good idea, i will post there shortly.
After you post here:
Which PWM, CPU or Specialty Fan do you Want SPCR to Review?
viewtopic.php?f=9&t=58350&start=30

Please read this thread and consider making a contribution, if you can.
5dBA 120mm Fan
viewtopic.php?f=9&t=61591

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"Aristotle calls man the rational animal. All my life I have been seeking evidence to confirm this" Bertrand Russell
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former" Albert Einstein


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 Post subject: Re: Fan curves: I can make them
PostPosted: Mon Feb 21, 2011 10:06 am 
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Joined: Wed Oct 06, 2010 6:32 am
Posts: 91
Location: new york
ces wrote:
Please read this thread and consider making a contribution, if you can.
5dBA 120mm Fan
viewtopic.php?f=9&t=61591

yes please


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 Post subject: Re: Fan curves: I can make them
PostPosted: Mon Feb 21, 2011 12:10 pm 
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Joined: Thu Feb 04, 2010 6:06 pm
Posts: 3395
Location: US
goatsandmonkeys wrote:
ces wrote:
Please read this thread and consider making a contribution, if you can.
5dBA 120mm Fan
viewtopic.php?f=9&t=61591
yes please


Do you find that discussion as disorienting as I do? :)

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"Aristotle calls man the rational animal. All my life I have been seeking evidence to confirm this" Bertrand Russell
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former" Albert Einstein


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 Post subject: Re: Fan curves: I can make them
PostPosted: Mon Feb 21, 2011 2:54 pm 
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Joined: Wed Oct 06, 2010 6:32 am
Posts: 91
Location: new york
ces wrote:
goatsandmonkeys wrote:
ces wrote:
Please read this thread and consider making a contribution, if you can.
5dBA 120mm Fan
viewtopic.php?f=9&t=61591
yes please


Do you find that discussion as disorienting as I do? :)

It's like, I think I get it, but I couldn't replicate the results.


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