The vibration stability of the drilling fluid lifting pump significantly impacts the safety and efficiency of deep-sea drilling. This study establishes a Fluid-Structure Interaction (FSI) dynamic analysis model of a six-stage centrifugal lift pump to analyze the excitation force characteristics and modal response under fluid action. A vibration test platform was constructed to conduct head-flow (H-Q) performance tests and investigate vibration characteristics across the full flow range (0-260 m³/h). A joint evaluation method based on the Root Mean Square (RMS) of vibration velocity and the Crest Factor (Cf) of acceleration is proposed. Combined with time-domain waveform characteristics, this method accurately identifies vibration risks and faults under off-design condition. The results indicate that the lift pump operates stably under rated conditions (1450 r/min, 126 m³/h). However, when the flow rate deviates from the rated value, the vibration exhibits strong nonlinear characteristics, and fault risk increases significantly. The optimal operating flow range for the pump under off-design conditions is determined to be 130-156 m³/h. This study provides a theoretical basis and engineering guidance for vibration optimization and fault prevention of multistage centrifugal pumps in deep-sea applications.
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