抄録
It is well known that centrifugal pump efficiency becomes worse with the decrease of pump size and specific speed. The small-sized pump with low specific speed, in which the impeller outlet velocity was larger, was designed by an optimum design method combined with blade surface singularity method The results show as follows : The semi-open impeller designed by the optimum design method, yielded the highest efficiency of 61% among test impellers in narrow tip clearance c/b_2. In larger c/b_2,however, the leakage loss becomes dominant and the efficiency of impeller with larger blade outlet angle is higher. This fact implies that the c/b_2 should be considered as an additional factor for optimum design.
