Investigation of the influence of the gap between impeller and diffuser in the pressure pulsation characteristics of a centrifugal pump

Abstract

The volute centrifugal pump is the core equipment in large-scale water transfer project. The instability of the unit during operation is mainly due to the hydraulic vibration inside the mechanical parts, and pressure pulsation in the “bladeless area” of impeller and diffuser is the main reason for the hydraulic vibration. This paper investigated the change of pump efficiency and head on different values impeller-diffuser gap, and comparatively analyzed the pressure pulsation characteristics of centrifugal pump. The findings demonstrated that the large gap between the impeller and diffuser, the higher pump efficiency and the lower head. The high pressure regions at the impeller outlet and diffuser inlet were significantly narrowed at gap values of 10 mm and 12 mm. With the increase of the gap, the distribution of the flow field in the impeller and diffuser region became more uniform and the intensity of pressure pulsation was decreased. While the gap value was 12 mm, for the impeller monitoring point on the pressure coefficient ranged within ±0.05. This study illustrated the impact of impeller-diffuser gap value on the internal pressure pulsation of centrifugal pumps, it offered as a certain reference for improving the operational stability of the pumps.