Component Analysis of Unsteady Hydrodynamic Force of Closed-Type Centrifugal Impeller with Single-Blade

Abstract

Closed-type centrifugal impellers with single-blade are widely used as sewage pumps. However, they are geometrically asymmetric, thus resulting in significant changes in the circumferential static pressure distribution of the impeller as it rotate, which is believed to drastically change the radial and axial thrusts. To improve pump reliability, it is therefore necessary to quantitatively understand unsteady hydrodynamic forces, and to clarify the behavior and mechanism of generated hydrodynamic forces. This study investigates the radial and axial thrusts acting on a single-blade centrifugal impeller by component analysis. As a result, the behavior of the components of the radial and axial thrusts was clarified. In the time-averaged value of the radial thrust of the hydraulic part, the pressure component is dominant and the momentum component acts in a direction that offsets the pressure component. Although the momentum component is dominant in the time-averaged value of the axial thrust of the hydraulic part, it is mostly offset by the pressure component.