Abstract: In order to analysis the cause of low-frequency pressure pulsations in vaneless centrifugal pump volute and it’s influence on monitor points’ pulsation, computational fluid dynamics(CFD) method is employed with shear stress transport(SST) turbulence model being selected. Based on the accuracy confirmation of calculation, unsteady calculations under 3 different conditions are conducted. According to the results, a low-frequency pulsation arises from volute outlet part makes the dominant frequency of the monitor points nearby equal to this frequency because of the distortion of streamline, also it can produce almost the same impact for the rest of the points in the volute, the amplitude of pressure pulsation is directly related to flow separation; these points have two significant frequency, low-frequency and blade passing frequency; due to streamline distortion, eddies appear on the cross-section near the tongue, it’s frequency is equal to the dominant frequency of monitor point in outlet part, this finding can indicate the root cause of low-frequency pressure pulsation is the eddies generated due to streamline distortion.

Key words: vaneless centrifugal pump;volute;computational fluid dynamics(CFD);low-frequency pressure pulsation;flow separation