Objective Addressing the prominent issue of blade pass frequency (BPF) excitation in marine centrifugal pumps, this study proposes a composite impeller design based on splitter blades.

Method Taking a certain shipboard centrifugal pump as the research object, numerical simulations and experimental tests are performed to analyze the internal flow characteristics and excitation behaviors. A novel composite impeller optimization scheme is proposed, which incorporates additional blades shorter than the conventional short splitter blades, alongside the existing long and short blades. By comparing the steady-state flow fields and unsteady performance before and after optimization, the underlying mechanism through which the composite impeller reduces fluid excitation is investigated. The effectiveness of the optimization is then experimentally validated.

Results The results show that the composite impeller reduces blade loading on the long blades and improves the uniformity of the impeller outflow. The standard deviation of the relative velocity at the impeller outlet is reduced by 5.9% compared to the conventional impeller and by 1.67% compared to the conventional splitter-blade impeller. The composite impeller effectively reduces overall pulsation intensity caused by unsteady internal flows, as well as pressure pulsations and radial force fluctuations at the impeller outlet. Specifically, the circumferentially averaged amplitude of overall pressure pulsations at the impeller outlet is reduced by 47.8% compared to the conventional impeller and by 21.7% compared to the conventional splitter-blade impeller. The blade frequency excitation force decreases from 0.42 N in the conventional impeller to 0.04 N in the composite impeller. The composite impeller significantly suppresses blade frequency line-spectrum excitation, with vibration intensity at the machine feet reduced by 92.4% compared to the conventional impeller and by 53.9% compared to the conventional splitter-blade impeller. Furthermore, the total low-frequency vibration level at the rated operating condition is reduced by 3.25 dB and 0.97 dB, respectively.

Conclusion The composite impeller design featuring splitter blades effectively reduces fluid-induced excitation in centrifugal pumps, surpassing the performance of conventional splitter blades. This study offers valuable insights for the design of low-vibration, low-noise centrifugal pumps.