7.31 The power, , required to drive a fan is depends on fluid density , volume flow...

7.31 The power,
, required to drive a fan is depends on fluid density

ρ, volume flow rate Q, impeller diameter D, and angular speed ω.

A fan with a diameter of 8 in. rotating at 2500 rpm delivers 15 ft3/s of air. Determine the diameter of a geometrically and dynamically similar fan rotating at 1800 rpm that delivers 88 ft3/s of air.