The impeller of a centrifugal fan is 320 mm in diameter and has backward curved blades. at a speed of 1460 rev/min the fan delivers 1,5 m3/s of air (rho = 1,2 kg/m3) against a total pressure of 350 pa. the manometric efficiency at this duty point is 60% and the whirl velocity at the impeller exit can be assumed to be twice the impeller peripheral velocity. taking the mechanical efficiency as 90%, calculate the power required to drive the fan