[ed_denu]

I think you're making this to complicated. Without some additional calculations, cfm is just a number. Actual air flow is affected by many things, duct size, dampeners, static pressure, etc. etc. A couple of other things to remember is that CFM is the AMOUNT of air coming through a duct. Velocity is the SPEED of air coming through a duct.

IMO most any cfm fan can be made to work, just add the ability to throttle the air flow by using a dampener or smaller duct and add a diffuser at the discharge point.