Describe, with the aid of sketches, the relationship between geometry and specific speed for pumps
a. A model centrifugal pump with an impeller diameter of 20 cm is designed to rotate at 1450 rpm and to deliver 20 dm3 /s of freshwater against a pressure of 150 kPa. Determine the specific speed and diameter of the pump. How much power is needed to drive the pump if its efficiency is 82%?
b. A prototype pump with an impeller diameter of 0.8 m is to be tested at 725 rpm under dynamically similar conditions as the model. Determine the head of water the pump must overcome, the volume flow rate, and the power needed to drive the pump.