Cavitation characteristics and experimental study on the first stage impeller of centrifugal charging pump

In order to study and improve cavitation performance of the first stage impeller of centrifugal charging pump in nuclear power plant, the numerical simulation was used for optimization and analysis. The number of the blades was changed to 4, and the best cavitation performance, the head and efficiency of pump were studied. The results show that in the maximum flow rate condition, the relative error of head between simulation and experimental results is 2.9% and the relative error of net positive suction head is 3.6%. The numerical results and experiment results are consistent. The cavitation is divided into 5 stages: incipient cavitation, developing cavitation, critical cavitation, severe cavitation and fracture cavitation. The analysis results indicate that the bubbles appear firstly in the inlet of the blade suction surface in incipient cavitation and they appear in the blade pressure surface after critical cavitation. The cavitation and dynamic and static interference in the pump body affect pressure fluctuation in the impeller between developing cavitation and severe cavitation. The cavitation plays a main role after severe cavitation, then pressure fluctuation becomes relatively stable and amplitudes of pressure fluctuation significantly reduce in the inlet and central part of the impeller, but pressure pulsation with relatively high amplitude and regularity still remains in the impeller outlet. (authors)