Investigation on the effect of complex impeller on vibration characteristics for a high-speed centrifugal pump

In this article, to improve the vibration characteristics of a high-speed centrifugal pump, two new types of complex impeller were designed for replacing the original long-blade impeller. The experimental apparatus of pump vibration was designed and used to test the vibration signals of the model pump with the original impeller in frequency field. The vibration amplitude of 0.12 mm/s2 is observed on the shaft rotating frequency, while the amplitudes of 0.04 mm/s2, 0.14 mm/s2, and 0.2 mm/s2 respectively on the conditions of 0.8 QN, QN, and 1.2 QN appear on the impeller blade passing frequency. The computational fluid dynamics method was used to study internal flow characteristics in the pumps with three impellers for mitigating the pump vibration. Steady pressure nephogram shows big pressure difference existed in the complex-impeller pump, which means that the complex impeller can provide the high-lift water. Addition of the splitter blade can make the pressure-fluctuation amplitude of model pump to reduce obviously by the unsteady time–frequency analyses. Furthermore, two complex impellers were machined and used to conduct the contrast experiment on the vibration characteristics between the pumps with the original impeller and complex impeller. The results reveal that the water head of pump with the complex impeller is higher than that of the original pump, which verifies the simulated results. Meanwhile, the complex impeller has a positive effect on the decrease of pump vibration on the frequency domain, especially on the blade passing frequency the vibration amplitudes decrease by 0.08 mm/s2.