摘要：This paper presents an experimental investigation of large-scale flow-field instabilities in a centrifugal pump impeller of low specific speed. Measurements of pump hydraulic performance and flow-field in the impeller passages were made with a hydraulic test rig and a Particle Image Velocimetry (PIV) system separately. Analyses of data and flow structures in the impeller passages were performed. Results showed that an unstable area existed in the range from 0.1 to 0.6 and had a close relationship with vortices in the impeller passages. With decreasing of flow rates, vortices experienced onset to expansion from 0.6 to 0.1 in visualization. was directly influenced by vortices between 0.1 and 0.6; and were significantly influenced by vortices from pressure side to the middle; however the slight impact was observed from the middle to suction side. Thus the experimental results could provide important evidence for the influence of flow instabilities on pump hydraulic performance.
