Re: Fan cooling , qualitative assessment

G

Guy Macon 18 years ago

For an existing product with a 12V fan with ducted area across fan ie minus

>the central motor area, of about 6 square inches and current consumption of
>.2 amps.
>As it stands this fan would seem to waste a lot of power and increase in
>noise, blowing through a set of 14 slots in the case of total air vented
>area 1.5 sq ins.
>If most of this grill section was totally cut away , fared off, and an
>external wire grill added would that allow the use of .1 amp fan for
> more, or less air throughput and a bonus of less audible noise.

If you reduce the 0.2A to 0.1A you will save 1.2W. Unless you are running on battery power, that's not "a lot of power."

14 slots with a total area of 1.5 sq inches? That would make them somewhere around 1 inch by 1/10 inch each. I am finding that hard to believe.

Is this just one that you own, or are you making a bunch of them? Wire grills cost more in parts and labor.

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N

N Cook 18 years ago

minus

of

14 punched slots 1.1 x .1 inches It is as much a noise problem. The .2 amp fan on its own in free air makes an acceptable amount of noise but forced to partially whistle through the slots , makes too much noise.

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M

mpm 18 years ago

I'm having trouble picturing your set up in a 3D world. No matter: I probably can't help anyway.

I just wanted to mention a company I worked for once tried to reduce fan noise on a large VME-type backplane device. The end result was the cards would fail when you tried to work on them with an extender card. I guess with the door open, the components just did not get enough air flow.

If the thing's whisteling, I wonder if making the holes (hole pattern) different would help? Possibly using a couple different sizes. Breaking up the air flow is the trick. It may not be a good analogy, but vortex shedding on long cylindrical object (such as broadcast TV antennas) has a related result - less singing, and less vibration on the structure. FWIW. -mpm

Vote

N

N Cook 18 years ago

minus

of

14 punched slots 1.1 x .1 inches It is as much a noise problem. The .2 amp fan on its own in free air makes an acceptable amount of noise but forced to partially whistle through the slots , makes too much noise.

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G

Guy Macon 18 years ago

Simple solution:

[1] Find whoever thought that those slots were an acceptible grill for a six inch fan and kill him. [2] Find someone who can preview your posts to sci.electronics.design, identify the places where someone trying to help you asked you a question and you didn't answer it, and poke you with a cattle prod until you learn. [3] Replace that grill with something that lets more air through. a 12 giuage shotgun should be able to make a big enogh hole.

I hope this helps...

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Re: Fan cooling , qualitative assessment

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