Study on characteristics of flow-induced excitation force in pump-source pipelines based on load identification method

Objective This study aims to determine the characteristics of fluid-induced excitation forces acting on piping structures driven by centrifugal pumps and other power equipment, thereby addressing the current insufficiency of research on fluid-induced vibration excitation forces in pump-driven pipelines and providing a theoretical foundation for vibration control of pump-driven pipeline systems.

Method Based on dynamic numerical models and measured vibration response data of the piping, a distributed fluid-induced load identification method is introduced to investigate the spectral characteristics and spatial distribution patterns of fluid-induced excitation forces in a pump-driven straight pipe system. Coherence analysis is further employed to quantitatively separate the acoustic source pressure wave and turbulent fluctuating pressure components of the fluid-induced excitation forces in the pump-driven pipeline.

Results The results show that the fluid-induced excitation forces exhibit significant broadband and line spectrum characteristics. The energy attenuation of the fluid-induced excitation forces during axial transmission along the pipeline is not obvious, and their attenuation rate with increasing frequency is significantly faster than that of the flow field's fluctuating pressure. An increase in flow velocity has a relatively small effect on the fluid-induced excitation forces acting on the pump-driven straight pipe. The line spectrum characteristics in the frequency spectrum of the fluid-induced excitation forces are primarily induced by the acoustic cavity modes of the pipeline fluid and the blade passing frequency of the centrifugal pump. The separation of coherent and incoherent components of the fluid-induced excitation forces based on coherence analysis demonstrates that the fluid-induced excitation forces within the pipe are dominated by spatially highly coherent acoustic source pressure waves, and that energy attenuation occurs during the transmission process in which acoustic waves are converted into transverse fluid-induced excitation forces.

Conclusion The characteristics of fluid-induced excitation forces in the pump-driven straight pipe are systematically summarized, and the dominant role of acoustic source pressure waves in the fluid-induced excitation forces of pump-driven pipelines is clarified for the first time. These findings provide a theoretical basis for vibration control of pump-driven pipelines.