Pressure fluctuation study in the stages of a multistage pump at best efficiency points under various operating speeds

Abstract

The interaction between the rotor and stator is a major source of high amplitude pressure fluctuation and flow-induced vibration in multistage centrifugal pumps. The pressure fluctuation is detrimental to the reliable operation of pumps. The sensitivity of vibration is severe if the number of stages is more. In the present experimental study, a vertical multistage centrifugal submersible pump is used to measure the pressure fluctuation level at Best Efficiency Points (BEP) and to determine the influence of stage and operating speed on pressure fluctuation. For this purpose, pressure fluctuation signals were captured at the delivery side of the pump at BEP at various speed settings. The characteristics of pressure fluctuation at BEP at various operating speeds were studied with the help of spectra, i.e., in the frequency domain. The amplitude variation of pressure fluctuation with harmonics of vane passing frequency at stages were studied. Results have indicated that variation of pressure fluctuation with stage and speed exhibited a non-linear variation. In addition, such a pressure fluctuation study will be helpful to modify the design to obtain a uniform pressure distribution in the stages of a multistage pump.