Statistical Characteristics of Suction Pressure Signals for a Centrifugal Pump under Cavitating Conditions

摘要

Centrifugal pumps are often used in operating conditions where they can be susceptible to premature failure.The cavitation phenomenon is a common fault in centrifugal pumps and always associates with undesired effects.Among the numerous cavitation detection methods, the measurement of suction pressure fluctuation is one of the most methods to detect or diagnose the degree of cavitation in a centrifugal pump.In this paper, A closed loop was established to investigate the pump cavitation phenomenon, the statistical parameters for PDF (Probability Density Function), Variance and RMS (Root Mean Square) were used to analyze the relationship between the cavitation performance and the suction pressure signals during the development of cavitation.It is found that the statistical parameters used in this research are able to capture critical cavitation condition and cavitation breakdown condition, whereas difficult for the detection of incipient cavitation in the pump, and the reason is also proposed.At part-load conditions, the pressure fluctuations at the impeller inlet show more complex than the best efficiency point (BEP), amplitude of PDF values of suction pressure increased steeply when the flow rate dropped to 40 m3/h (the design flow rate was 60 m3/h), one possible reason is that the flow structure in the impeller channel promotes au increase of the cavitation intensity when the flow rate is reduced to a certain degree.This shows that it is necessary to find the relationship between the cavitation instabilities and flow instabilities when centrifugal pumps operate under part-load flow rates.