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Fan cooling , qualitative assessment

Discussion in 'Electronic Design' started by N Cook, Aug 23, 2007.

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  1. N Cook

    N Cook Guest

    Without having to learn about pneumatics
    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.
     
  2. Guy Macon

    Guy Macon Guest

    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.
     
  3. N Cook

    N Cook Guest

    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.
     
  4. mpm

    mpm Guest

    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
     
  5. N Cook

    N Cook Guest



    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.
     
  6. Guy Macon

    Guy Macon Guest

    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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