Study on dynamic characteristics of centrifugal pump with the development of cavitation under low temperature conditions

The thermodynamic effect of centrifugal pump cavitation was different at different water temperatures. There was a gap in the research on the modulation frequency of centrifugal pump under the effect of low temperature cavitation heat. Therefore, the development of centrifugal pump cavitation and the change of dynamic characteristic modulation frequency under low temperature conditions were discussed in this paper. In this study, the cavitation distribution, pressure pulsation, noise and vibration of centrifugal pumps at different speeds under the conditions of low temperature water (5 °C) and room temperature water (25 °C) were analyzed and compared by using fast Fourier transform (FFT) and a novel demodulation method for principal component analysis (DPCA). The cavitation was divided into four stages: non-cavitation stage, incipient stage, quasi steady stage, unstable stage. The results show that the outlet pressure pulsation and noise of the centrifugal pump was mainly modulated by Blade Passing Frequency (BPF). Compared with 25 °C, the pressure pulsation modulation amplitude of BPF was reduced by 22.6%, the noise modulation amplitude was reduced by 18.8% at 5 °C. In the non-cavitation stage and the cavitation incipient stage, the vibration of the centrifugal pump was mainly modulated by Axis Passing Frequency (APF), 2APF, 4APF, and in the quasi steady stage and unstable stage, it was mainly modulated by APF and BPF. Compared with 25 °C, the amplitude of vibration modulation of APF was reduced by 6.7%; that of 2APF was reduced by 29.7%; that of 4APF was reduced by 16.5%, and that of BPF was reduced by 37.3% at 5 °C.