# Suppose the pump of Prob. 1467 has some reverse swirl at the inlet such that 1 = 10 instead

## Question:

Suppose the pump of Prob. 14–67 has some reverse swirl at the inlet such that α1 = –10° instead of 0°. Calculate the net head and required horsepower and compare to Prob. 14–67. Discuss. In particular, is the angle at which the fluid impinges on the impeller blade a critical parameter in the design of centrifugal pumps? Does a small amount of reverse swirl increase or decrease the net head of the pump— in other words, is it desirable?

Data from Problem 14–67

A centrifugal pump rotates at ṅ = 750 rpm. Water enters the impeller normal to the blades (α1 = 0°) and exits at an angle of 35° from radial (α2 = 35°). The inlet radius is r1 = 12.0 cm, at which the blade width b1 = 18.0 cm. The outlet radius is r2 = 24.0 cm, at which the blade width b2 = 16.2 cm. The volume flow rate is 0.573 m3/s. Assuming 100 percent efficiency, calculate the net head produced by this pump in cm of water column height. Also calculate the required brake horsepower in W.