Objective Aiming at the prominent issue of blade pass frequency (BPF) excitation in marine centrifugal pumps, a composite impeller design based on splitter blades is proposed.

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

Results 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 the 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. The composite impeller significantly suppresses blade frequency line-spectrum excitation, with the 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 based on splitter blades further reduces fluid-induced excitation in centrifugal pumps beyond what is achievable with conventional splitter blades. This study provides valuable guidance for the design of low-vibration and low-noise centrifugal pumps.