Numerical Study on the Characteristics of Pressure Fluctuations in an Axial-Flow Water Pump

Flow induced vibration due to the dynamics of rotor- stator interaction in an axial- flow pump is one of the most damaging vibration sources to the pump components, attached pipelines, and equipment. Three- dimensional unsteady numerical simulations were conducted on the complex turbulent flow field in an axial- flow water pump, in order to investigate the flow induced vibration problem. The shear stress transport (SST) k-omega model was employed in the numerical simulations. The fast Fourier transform technique was adopted to process the obtained fluctuating pressure signals. The characteristics of pressure fluctuations acting on the impeller were then investigated. The spectra of pressure fluctuations were predicted. The dominant frequencies at the locations of impeller inlet, impeller outlet, and impeller blade surface are all 198 Hz (4 times of the rotation frequency 49.5 Hz), which indicates that the dominant frequency is in good agreement with the blade passing frequency (BPF). The first BPF dominates the frequency spectrum for all monitoring locations inside the pump.