Investigation on Pressure Fluctuation of the Impellers of a Double-Entry Two-Stage Double Suction Centrifugal Pump

Double-entry two-stage double-suction centrifugal pumps with high flow rates and high heads are used in some large water supply applications. The pressure fluctuation of the impeller is a key factor influencing the vibration in centrifugal pumps. In this paper, the pump is simulated and verified by experiments, and the pressure fluctuation distribution of two stage impellers is obtained. The study on the time domain and frequency domain of the two-stage impellers demonstrates that the pressure fluctuation of the first-stage single-suction impeller is affected by the twin volute. At 1.0 Q, the dominant frequency on the blade suction side and pressure side is twice the rotation frequency. The main frequency of pressure fluctuations at the outlet side of the blade at a low flow rate is higher than that at the design flow rate. Pressure fluctuations in the second-stage impeller are influenced by the inter-stage passage. The dominant frequency amplitudes grow incrementally along the streamlined direction. In the second-stage double-suction impeller, the dominant frequency amplitude at 0.6 Q is approximately twice that of 1.0 Q. Research in this paper can guide the design and operation of a two-stage pump.