Improvement of Suction Performance of Centrifugal Pump Impeller : Effects of Leading Edge Extension of Every Other Blade and Splitting of the Impeller

Abstract

An experimental study of suction performance was carried out on the centrifugal pumps with impellers made by extending every other blade of the ordinary impeller with six blades toward the suction opening and tandem-bladed impellers made by cutting off the extended blade section of the above impellers from the original impeller. Principal results are as follows. (1) A suction specific speed comparable but not superior to that of the tandem-bladed impeller was obtained by the impeller with extended blade. (2) The suction periformance of tandem-bladed impeller is strongly affected by the relative axial and tangential position of the front blade row to the rear blade row. (3) The suction performance deteriorates rapidly in the excess flow rate range of the extended blade type impeller, but it is not so severe as for the tandem-bladed impeller.