Cavitation-induced vibration and noise signal analysis of a single blade centrifugal pump

This study investigates the cavitation-induced vibration and noise characteristics of a single blade centrifugal pump through integrated numerical simulations and experimental analyses. Numerical simulation was used to characterize the flow field at different cavitation stages in the pump. In the cavitation closed test bench, vibration sensors and hydrophones concurrently capture vibration and noise. The characterization of cavitation signals was analyzed using time-frequency decomposition, energy entropy, and vibration acceleration level (La). Key results indicate that initial cavitation generates intermittent high-frequency (1.5–3.5 kHz) vibration shocks. Under mild cavitation conditions (NPSHa = 4 m), the La value increases by 6% compared to the non-cavitation state, and the amplitude of the dominant frequency increases by 42%. Additionally, the dominant energy of the primary modal function IMF1 increases by 66%, highlighting the significant enhancement of high-frequency excitation. Noise spectra show a 28 dB reduction at the blade-passing frequency (49 Hz) due to cavitation bubble collapse, alongside amplified low-frequency (200–600 Hz) components and attenuated high-frequency sound pressure (75% of baseline). The energy entropy obtained based on the Hilbert–Huang transform peaks at 1.77 for mild cavitation and decreases to 1.02 in the severe phase, which reflects the nonlinear modulation effect. These findings establish quantifiable relationships between cavitation advancement and the characteristics of pump vibration and noise, offering a framework for monitoring cavitation in pumps processing impurity-laden fluids.