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

[JohnPinnacle]

Hello,

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!
John

 

[Mech_Engineer]

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.