Centrifugal-Pump Performance as a Function of Specific Speed

The object of this paper is to examine the performance of centrifugal pumps as a function of specific speed. Based on established gross pump efficiencies, hydraulic efficiency is evaluated by eliminating mechanical and leakage losses. General laws of variation of disk friction and leakage losses with the specific speed are established. A special study is made of leakage losses, and coefficients necessary for calculation of flow through small annular clearances are given as function of Reynolds number. Knowing hydraulic efficiency, hydraulic losses are calculated, and these in turn permit determination of the necessary experimental coefficients for improved formulas for the theoretical head developed by impellers of centrifugal pumps.