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

by JohnPinnacle
Tags: areas, calculation, inlet, outlet
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Jul27-12, 08:56 AM
P: 3

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!
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Jul27-12, 10:01 AM
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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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