Instantaneous Interblade Pressure Distributions and Fluctuating Radial Thrust in a Single-blade Centrifugal Pump

Abstract

Although single-blade centrifugal pumps are frequently used to handle waste water with solids, they have poor durability because they show severe vibration caused by a fluctuating radial thrust. Very few reports on the fluctuating radial thrust of turbo-machines have been published to date. Hence, details of the behavior and mechanism of the fluctuating radial thrust remain unclear, and a method for reducing the fluctuation is not established. In this report, instantaneous blade surface pressure distributions affected by volute pressure distributions are measured on the suction cover surface of a pump with an open-type centrifugal impeller having one blade. The fluctuating radial thrust mechanism is then clarified on the basis of these measurements, and a difference between actual radial thrust and the integrated value of static pressure along the impeller outlet is discussed. Furthermore, the radial thrust is separated into dynamic and static radial thrust vectors and a method for reducing the dynamic components, which are the cause of pump vibration, is demonstrated.