Abstract:  In order to study the cavitation phenomenon of centrifugal pump under large flow condition and the relationship between cavitation and pressure pulsation under the condition, through experimental test, the monitoring points were established in the volute for numerical analysis, the pressure pulsation of centrifugal pump in different cavitation stages under large flow condition was studied, and the unsteady cavitation flow characteristics of centrifugal pump were analyzed. Firstly, the external characteristics and different degrees of cavitation of centrifugal pump were tested by building a closed pipeline test-bed. Then, RNG k-ε turbulence model and full cavitation model were used to calculate a single-stage single suction cantilever centrifugal pump, and the time-domain and frequency-domain characteristics of cavitation flow field and pressure pulsation at monitoring points P1~ P5 on volute were obtained. Finally, based on the numerical results, the steam volume fraction, the velocity vector distribution of the middle section and the pressure pulse at the monitoring point under different cavitation conditions in the impeller were analyzed. The research results show that with the intensification of cavitation, the cavitation area on the suction surface of the blade continues to expand, the blocking effect on the inlet of the flow channel gradually increases, and the main frequency of each pressure pulsation monitoring point on the pump volute also changes significantly. Therefore, the monitoring and analysis for pressure fluctuations on the pump volute can provide reference for the assessment of cavitation phenomenon.
Key words:  centrifugal pump;cavitation degree;cavitation stage;cavitation flow characteristics;turbulence model;full cavitation model; pressure fluctuation; rotorstator interaction