Cavitation-vibration correlation of a mixed flow pump under steady state and fast start-up conditions by experiment

Abstract

Cavitation and vibration are crucial characteristics in pumps, which directly contribute to the safe and stable operation of pumps. Cavitation and vibration are both complicated phenomena in pumps, and their correlation is still not sufficiently revealed. In the present work, a synchronous experimental system including the test pump, high-speed camera and sensors is built to measure cavitation and vibration of the pump under steady state and fast start-up process with different accelerations of rotational speed. Results show that there is a strong correlation between cavitation and vibration, and high-amplitude vibrations start to appear and concentrate in the range of 1200–1400Hz after cavitation occurrence. In fast start-up processes with different acceleration times, there are two peaks in pump head due to the flow impact and pump hump, and the short acceleration time will lead to cavitation suppression. A new criterion method is proposed by definition of a dimensionless parameter of power ratio r, which divides the vibration power in 1200–1400Hz by the vibration power in 0–200Hz, to judge the cavitation occurrence. When the power ratio r is over 2.00, the cavitation occurs. Finally, the new criterion method is validated in both steady state and fast start-up conditions by experiment.