Vibro-acoustic responses of coupled pump-jet-hull model under duct excitation and the influence of shafting support modes

The vibro-acoustic characteristics of coupled pump-jet-hull system under excitations on the wall of duct are investigated. The fluid excitation of duct is simulated using computational fluid dynamics. The different vibro-acoustic characteristics for excitations on inner and outer wall of duct are contrastively investigated through establishing a finite element model and boundary element model of coupled pump-jet-hull system. Meanwhile, the influence of shafting support modes on vibro-acoustic responses is discussed. The results show that the source of excitation forces on inner and outer wall is different. The force spectra of inner wall exhibit a line spectrum characteristic, reflected in blade passing frequency, while the force spectra of outer wall show a broadband characteristic. The vibration response as well as sound radiation are mainly contributed by hull modes. The acoustic radiation power excited by forces on inner wall is slightly dominant in the low frequency range. The duct excitation can cause a coupling resonance of the shafting system and it is insensitive to the shafting support modes.