Application of spectral analysis techniques to cavitation in centrifugal pumps

Abstract

ABSTRACT An experimental investigation has been performed to study the inception of cavitation and the effect of entrained air on cavitation in a double suction centrifugal pump. Experiments have been organized to cover off-design flow rates and reduced suction pressures independently so that has been possible to study both the effect of flow rate and suction pressure. Air of known amounts has been entrained from the suction pipe to investigate its effect on the intensity of cavitation and the performance of the pump. Pressure transducers and a FM tape recorder have been used to record the pressure signals acquired from three locations on the set-up. Consequently the data has been digitized and processed by spectral analysis techniques. The power spectra and the RMS values of the pressure signals have been investigated to reveal the inception and extend of cavitation as well as the effect of entrained air. As a result of the study carried out, it has been possible to conclude that spectral analysis techniques are useful tools for the detection of the inception and extend of cavitation and that although having some cushioning effect at the suction side of the pump air entrainment is not an effective method in reducing cavitation damage.