In order to further probe the relations between hydraulic features and instantaneous vibration of impeller pump, an axial flow pump designed with different combination schemes of rotor and stator is numerically investigated. Vane numbers of 5, 7 and 9 are separately adopted to match the same impeller with 4 blades. Attentions are paid on the pump's performance under low flow rates. Saddle-shaped performance curves are proved during the three pumps' operation with the variation of flow rate. With pre-defined non-dimensional parameters, distributions of axial velocity near the impeller and vane are described. Pressure waves and wake in the region between impeller and vane influence significantly the turbulent flow patterns and energy dissipation. Typical frequencies achieved through fast Fourier transformation of fluctuating pressures also indicate that the emergence of low-frequency components and energy dissipation in the rotor-stator interaction(RSI) region arouse more non-deterministic factors of hydraulic excitation.
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