Experimental study on vibration characteristics of water-jet pump under different cavitation conditions

Cavitation generates abnormal excitation force in the internal flow field of the water-jet pump, and then induces the vibration of the pump body, which will directly threaten the navigation safety, stealth performance, and equipment service life of the ship. To accurately reveal the vibration mechanism of water-jet pump under different cavitation stages, the vibration acceleration signals of guide vane bearing foot and elbow bearing foot of water-jet pump are collected through vibration test, and the vibration characteristics of water-jet pump along the X -axis, Y -axis, and Z -axis are systematically analyzed. The findings indicate that the vibration acceleration spectrum characteristics are significantly affected by the cavitation intensity. The amplitude of the dominant frequency in the low frequency band is related to the frequency of the impeller blades, while the broadband signals in the high-frequency band are induced by cavitation. Additionally, the signal intensity of each frequency band increases with the development of cavitation, but the vibration acceleration is partially suppressed during the first critical cavitation stage. According to the analysis of vibration acceleration energy, the vibration energy at different measurement points and in different directions exhibits an upward trend with the cavitation development, but the variation pattern is different. These research outcomes offer critical experimental data and theoretical backing for studying cavitation-induced vibration mechanisms, and hold direct engineering significance for the design of water-jet systems.