Study On The Characteristic Analysis And Identification Of Vibration Source In Axial-flow Pump

Axial-flow pumps are widely used in various fields such as irrigation,hydroelectric generating units and waterjet propulsion in warship, etc. The stability ofaxial-flow pump in the operation process has been the focus of our concern. The poorstability may cause noise and vibration which will affect the operating performance oreven cause serious safety accident.The vibration of mechanical structure and the pressure pulsation are the mainfactors affecting the stability of axial-flow pumps. In this paper, the method ofphysical model test was used to collect the pressure pulsation and structure vibrationsignal in an axial-flow pump at different flow rate. Then the frequency and amplitudedistribution were analyzed. As a result, the characteristics of pressure pulsation andstructure vibration were obtained. Meanwhile，the modal frequencies of the pumpwere tested by experimental modal analysis method.Based on the multi input/single output model, the partial coherence analysis wasdone to identify the main vibration source of axial-flow pump. The partial coherencefunction and the output spectrum of each vibration source were calculated. The resultsshow that, the vibration of mechanical structure is the main excitation source at theoptimum flow rates.In the transient operation process, the pressure pulsation features nonstaionarity.In this paper, a method based on EEMD and Hilbert transform were applied toanalyze pressure pulsation signal in an axis-flow pump. The results show that thismethod can accurately identify the frequency components and the time variation ofpressure pulsation signal.