Power Number

Written by Matt Milbury. Posted in Rotating Equipment

Power Number is a dimensionless number about the power used by fans, mixers and pump impellers at a specified rotational speed.

Formula

\(N_p = \frac { P  } { n^3 d^5 \rho}\)

Where:

\(N_p\) = Power Number

\(P\) = impeller power

\(n\) = impeller rotational speed

\(\rho\) = fluid density

\(d\) = impeller diameter