Tests for flow induced characteristics of a centrifugal pump under air-water two-phase inflow condition

A two-phase flow pumping test platform was built to study flow induced characteristics of a centrifugal pump under air-water two-phase inflow condition. The pump characteristics were measured when its ratio rotating speed ns=132.2. Under different flow rates and inlet air voids, the pump's outer characteristics, pressure pulsation, vibration signal frequency spectra and their probability density figures were obtained. The study results showed that the performance of the centrifugal pump is more sensitive to air under the conditions of small flow rate and air-water two-phase inflow; its performance drops sharply when inflow air void is more than 8%,and the range of working conditions that can be tested becomes narrower and more chaotic, the maximum air void of the pump can reach 10%; the main frequency of the pump outlet pressure pulsation is the blade frequency under air-water two-phase condition, vibration amplitude at the blade frequency increases with increase in inlet air void; the larger the inlet air void,the more obvious the broadband characteristics of the low frequency field; pressure fluctuation signals and vibration signals obey the normal distribution; with increase in inlet air void, the probability density function (PDF) amplitude of pressure pulsation decreases gradually, while its span becomes wider gradually; the PDF amplitude of vibration increases firstly and then decreases, and reaches the minimum when inlet air void is 5%, furthermore it has a rising trend; both pressure fluctuation and vibration variations can be used as important bases for flow state monitoring. © 2019, Editorial Office of Journal of Vibration and Shock. All right reserved.