Study on the Influence of Blade Circular Cutting on the Flow-induced Noise of Centrifugal Pump

In order to study the influence of blade exit circular cutting on pressure fluctuation and flow-induced noise of centrifugal pump, six kinds of blade cutting schemes were designed by changing chord height by fixed circle chord length. RNG k-ε turbulence model was used to calculate the whole flow field of external characteristics and pressure pulsations of each design scheme. Based on Lighthill sound analogy theory and BEM, the internal acoustic field was calculated. The results show that the design scheme of impeller blade after cutting are compared with the original scheme, the pressure fluctuation at axial frequency, and blade frequency and double blade frequency are improved obviously. When the ratio of chord height to blade outlet width is 0.333, the pressure fluctuation amplitude of the design condition reaches the lowest. When the ratio of chord height to blade outlet width is 0.167, the inlet sound pressure level decreases by 3.5 dB and the exit sound pressure level decreases by 3.4 dB. With the continuous increase of the circular cutting area, the sound pressure level of each scheme shows the characteristics of decreasing first and then increasing and then decreasing. With the increase of the circular cutting area at the blade exit, the head drop in the working range of 0.6 Q_v~1.4 Q_v has positive correlation with the increase of the circular cutting area, but the effect on the efficiency of the centrifugal pump is less.