Experimental Investigation of Relationship Between Pressure Fluctuations and Vibrations for a Double Suction Centrifugal Pump

Abstract

Double-suction centrifugal pumps are widely employed in large-scale pumping stations, which generally run in the conditions of large discharge with huge energy consumption. Pressure fluctuation caused by internal flow due to tongue-impeller interaction is the primary source of pump vibration. In this paper, pressure fluctuations and vibrations signals on volute casing wall were experimentally obtained at five flow rates ranging from 59% to 121% of nominal flow rate. Time and frequency domains of the signals were mainly analyzed by using statistical and fast Fourier transform methods. The results show that rotational frequency, blade passing frequency and their harmonic frequencies of pressure fluctuations as well as vibrations are clearly identified. The magnitude at blade passing frequency has close relationship with the measurement location related to the volute tongue, and becomes larger when the flow rate deviates from the nominal flow rate. The magnitudes at blade passing frequency can increase by 70% and 151% at high flow rate over that at the nominal flow rate for pressure fluctuations and vibrations, respectively. While the magnitude of vibration at rotational frequency keeps nearly constant at partial flow rate, and decreases at high flow rate.