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The axial-flow impellers are widely applied to industry due to their excellent hydraulic performance and simple structure, but they may be affected by their eccentricity during operation. This study compared and studied the effects of the axial-flow eccentricity of an impeller on hydraulic performance, impeller radial force, and downstream pressure pulsation of the unit. The research results indicate that impeller eccentricity has a small effect on hydraulic performance. Compared with the design conditions, the efficiency, power, and head changes caused by impeller eccentricity are all less than 1%, but the impeller eccentricity leads to a sharp increase in the radial force of the impeller. Under the design conditions, the average value of the radial force of the impeller is 31.38 N; under eccentric conditions, the average value of the radial force of the impeller increased by nine times, reaching 316.30 N. By analyzing the pressure pulsation signals decomposed by the VMD method, it is shown that the influence of eccentricity on pressure pulsation is mainly reflected in the increase in impeller frequency on pressure pulsation. Under design conditions, the corresponding amplitude of the impeller frequency is 2.6; under eccentric conditions, the amplitude corresponding to the impeller frequency increased by 100 times, reaching 274.4. This study elucidates the specific effects of axial impeller eccentricity, providing theoretical guidance for the safe and stable operation of axial-flow units, and has important engineering significance. [ABSTRACT FROM AUTHOR]

This paper aims to analyze the leading edge cavitation of a double-suction centrifugal pump, focusing on its periodic evolution process and unsteady characteristics. The calculation of external characteristics and the simulation of the leading edge cavitation in the double-suction centrifugal pump were performed based on the turbulent viscosity correction model. The cavitation was studied under three working conditions (0.5, 0.9, and 1.2 times the design flow rate). The position and structural characteristics of the leading edge cavitation were identified. The instability phenomenon and vortex motion in the impeller passage caused by cavitation were analyzed. The results indicate the inlet flow of the impeller and the pressure distribution on the blade surface are the primary factors influencing the characteristics of the leading edge cavitation. The inlet flow of the impeller determines the position of the leading edge cavitation, while the pressure distribution on the blade surface dictates the specific shape and structure of the cavitation. Throughout the development cycle of cavitation, the position of the flow instability region within the impeller shifts from the off-flow area of the leading edge to the tail of the cavitation region. [ABSTRACT FROM AUTHOR]

Mixed‐flow pump is a typical pump using in low‐head cases of water lifting. The flow field pulsation is usually an important issue in the operation of mixed‐flow pumps and their pumping statins. Due to its large size, it is difficult to monitor the internal flow characteristics well, based on computational fluid dynamics, we use 5678 monitoring points which arranged in the impeller and fixed vane with using the high pulsation tracking network, and the pressure pulsation signals are analyzed by fast Fourier transform and variable mode decomposition to decompose the main frequency and intensity of the pressure pulsation signals, then analyze the energy dissipation with the entropy production rate (EPR). It is found that there are strong low‐frequency (0.416, 0.625, and 1.67 Hz) pressure pulsation near hub, and the pressure pulsation on the shroud is stronger than that on the hub (at least three times or more); there are strong and stable pressure pulsation (25 Hz) on the shroud generated by the rotor–stator interference (RSI); and the EPR in the flow field can be well combined with the signal. Reasonably allocating material strength and controlling the number of vanes and impellers to avoid producing a common multiple can avoid pressure pulsation caused by RSI and reduce energy dissipation. Therefore, it is very effective in improving the efficiency of this part. Under low flow conditions, the siphon outflow passage can predict the high‐frequency (45.833 Hz) attenuation area well through the phase signal decomposition of the signal, which has certain significance for improving its stability and efficiency. [ABSTRACT FROM AUTHOR]