This paper investigates the hydrodynamic characteristic of a single-stage centrifugal pump with inlet inducer and outlet Radial Guided Vanes (RGVs) influenced by the clocking effect for the first time. Different from general ones, the outlet RGVs in this paper have specificities. The hydraulic performance and dynamic characteristics of the centrifugal pump are numerically studied and validated by experiments. The results indicate that there is an optimum position of RGVs that can not only increase the pump head and efficiency but also reduce the pressure fluctuation intensity. A non-dimensional parameter describing the velocity non-uniformity of the impeller outlet is first proposed, which is negatively related to the pump's hydraulic performance. The clocking position of the RGVs will affect the velocity homogeneity at the impeller outlet, and further influence the hydraulic characteristics of the pump. Besides, the clocking effect of outlet RGVs mainly affects the amplitudes of BPF for both the pressure fluctuation and radial force, and the most obvious frequency of pressure pulsation and radial force is 3 BPF correlating with the inlet inducer. It is recommended to install the volute-tongue tip near the middle of two vanes.
The complex three-dimensional turbulent flow field in a centrifugal water pump is numerically simulated considering torsional vibration of the shaft. The characteristic frequency and the frequency modulation phenomenon is investigated when the fluctuated-rotation-speed is considered. The results show that the amplitude of pressure fluctuation is bigger when the rotating-speed of shaft is unsteady, indicating that the speed fluctuations of impellers intensify the nonuniformity and instability of the whole flow field inside the pump. Besides, the Blade Passing Frequency (BPF) has obvious sidelobe frequency peaks when different frequency rate of speed appears. It can be concluded that sidelobes maybe come from the torsional vibration of the shaft. The main findings of this work can provide prediction of the pump performance and information for further optimal design of centrifugal pumps as well.
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