Abstract: In order to study the clocking effect on the unsteady pressure fluctuations in the centrifugal pump with a vaned diffuser, the three-dimensional unsteady numerical simulations are undertaken to analyze the inner flow characteristics with 5 different positions of diffuser by solving the RANS equations with SST k-ω turbulence model under 60% and 162% of the design conditions. The pressure fluctuation intensity distributions caused by the clocking effect in the diffuser and the volute are obtained. The results show that the clocking effect of diffuser on pressure fluctuation intensity due to the rotor-stator interaction is obvious. In the diffuser, the highest pressure fluctuation intensities occur at the throat area and the pressure side near the leading edge. The pressure fluctuation intensity propagates and weakens along the diffuser passage. Pressure fluctuation intensity distribution due to the clocking effect is irregular significantly. Under the partload condition in the diffuser, when the diffuser position is C3, the maximum value of the pressure fluctuation intensity is 0.44; when the diffuser positions are C2 and C4, the maximum values are 0.24 and 0.22, respectively. Under the overload condition in the diffuser, when the diffuser position is C2, the maximum value of the pressure fluctuation intensity is 0.87; when the diffuser positions are C1 and C4, the maximum values are 0.72 and 0.77, respectively. The pressure fluctuation intensity is much smaller than that in the diffuser under the partload and overload operating conditions. The relative position C4 can decrease the pressure fluctuation intensity and the result can provide a reference to the setting relative position of the diffuser to the volute.

Key words: centrifugal pump, clocking effect, diffuser, pressure fluctuation intensity, rotor-stator interaction