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CFM calculation with a known fan and different inlet and outlet areas

  1. Jul 27, 2012 #1

    Here are the known's of a chassis:
    Inlet open area = 17 inches^2
    Outlet open area = 30 inches^2
    Internal Fans = 270 cfm (3 fans @ 90 cfm each)

    What is the CFM through the system and what's the equations used to figure this out?

    I assume that if we had a very small inlet or outlet open area the pressure will build and decrease the CFM. I want to know if my fans will be choked or if they will run at 270cfm.

    Thanks a ton!
  2. jcsd
  3. Jul 27, 2012 #2


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    Science Advisor
    Gold Member

    There's just no way to answer your question with any certainty given the small amoutn of information you've provided. Personally I don't think it would be particularly difficult to flow 270 cfm through 17 in^2, but it depends on a lot more than just area.
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