Impact of impeller wake on the energy fluctuation characteristics of centrifugal pumps under rotating stall condition

To reveal the impact of impeller wake flow on the internal energy fluctuation of centrifugal pump, in this study, the performance and internal flow structures of centrifugal pumps under various operating conditions have been thoroughly analyzed by combining numerical simulations with experimental validation. The results indicate that the numerical simulation results are highly consistent with the experimental data in terms of head and efficiency, with an error of less than 5%, demonstrating the high accuracy of the simulations. Further investigation reveals a significant increase in entropy production loss under critical and deep stall conditions, primarily concentrated in the blade wake flow and the volute tongue interference region. Analysis of entropy production maps and pressure fluctuations under different operating conditions shows that the breakup of blade wake vortices and their interaction with the tongue are the main causes of high entropy production values. Coherence studies of pressure and entropy production fluctuations in the low-frequency range indicate a bidirectional interference mechanism between the two. Overall, this study provides important theoretical and data support for understanding the performance and loss mechanisms of centrifugal pumps under complex flow conditions.