Abstract
Numerical simulation and experimental method are combined to investigate the pump inlet and outlet pressure fluctuations, the vibration characteristics and the internal flow instabilities under the unsteady cavitation condition in a centrifugal pump. It is found that the unsteady cavitation starts to generate as the NPSHa is lower than 5.93 m. Apparent asymmetric and uneven cavity volume distribution on each blade and in the impeller can be observed as the NPSHa decreases from 4.39 m to 1.44 m, which includes the cavitation develops from cavitation surge, rotating cavitation to asymmetric cavitation. The flow vortexes in each blade channel are produced in the cavity trailing edges by the shedding and collapse of cavitation, which interfere with each other and aggravate the flow instabilities. The dominant frequencies of the pump inlet and outlet pressure fluctuations are the shaft frequency and blade passing frequency under the unsteady cavitation conditions, respectively. Broadband pulses are obtained from both the pump inlet and outlet pressure pulsations, which results from the random shedding and collapse of unsteady cavitation bubbles. Obvious corresponding relationship between the root mean squares of the vibration measured in different positions and the suction performance curve is found under both the non-cavitation and unsteady cavitation conditions.
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Recommended by Associate Editor Sangyoup Lee
Jiaxing Lu is currently a Ph.D. candidate in the National Research Center of Pumps, Jiangsu University. His research interests include the cavitation instabilities and analysis of unsteady flow of centrifugal pump. He received his B.S. degree from Xihua University in 2007.
Shouqi Yuan is currently a Professor in the National Research Center of Pumps, Jiangsu University. His research interests include the theory, optimization, and design of fluid machinery. He received his Ph.D. degree from Jiangsu University in 1994.
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Lu, J., Yuan, S., Siva, P. et al. The characteristics investigation under the unsteady cavitation condition in a centrifugal pump. J Mech Sci Technol 31, 1213–1222 (2017). https://doi.org/10.1007/s12206-017-0220-3
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DOI: https://doi.org/10.1007/s12206-017-0220-3