Research of transient rotor-stator interaction effect in a mixed-flow pump under part-load conditions

In order to analyze the unsteady flow characteristic and the pressure fluctuation features of mixed-flow pump caused by the interaction between the impeller and guide vanes under part-load conditions, the unsteady flow field in the mixed-flow pump was numerically simulated based on the standard k-epsilon turbulence model. The pressure distribution and the velocity distribution in the rotor-stator interaction (RSI) zones were acquired, and the time domain and frequency domain of the pressure fluctuation were emphatically analyzed. The results showed that the velocity within the rotor-stator interaction zones is mainly affected by the relative position of impeller and guide vane. With the decrease in flow rate condition, the flow fields become more violent and more vortexes generate in the RSI zone, which causes much energy losses. With the rotation of impeller, the vortexes generating from RSI zones move into the guide vane and dissipate in the guide vane passage in the end. The pressure pulsations at various monitoring points fluctuate periodically, and there appear four peak and four trough values with the same number of leaves. The dominant frequency of pressure pulsation was approximate to the impeller blade passing frequency (BPF). Within the rotor-stator interaction zones, the pressure pulsation coefficient in the rotor-stator interaction zone of the mixed-flow pump changes most obviously. The BPF and double and triple frequency of the pressure pulsation are dominant frequencies, and the frequency distribution range is relatively concentrated.