Radial fan flow rate.

[Keplerx]

Hi from Mexico.I am looking for a "formula" to find the flow rate of a radial fan. I only know Q is proportional to D(diameter) and to the RPM. There is a formula in turbomahcinery stating that the discharge can be computed by the formula Q=2(PI)rbV, where r is the radius,b is the blade width at r, and V is the velocity. Can this formula be used for a radial fan?. If not, is there exist a theorical formula to calculate he flow rate of a radial fan?. Thanks so much.

 

[MintJulep]

There is not a universal formula that works for any fan. You need to get the characteristic curves for your particular fan from the manufacturer.

 

[imok2]

This may be of some use to you.

http://www.electronics-cooling.com/html/2001_may_techbrief.html

 

[lilliput1]

The efficiency is the big unknown. Also there is a high pressure limit depending on the type of fan. Look at existing radial fan catalog. The basic fan equation is

Fan bhp = (CFM x tsp)/(6344 x eff)

Where tsp = in. wg total pressure
eff = decimal efficiency . We typically use 0.65 for centrifugal fans to come up with quick approximation of hp.