The effect on the vibration and acoustic radiation of the whole submarine due to the vibration of propeller blades under vertical excitation

  Objectives  The effect of propeller on the structural vibration and acoustic radiation of submarine is studied.

  Methods  As such, the acoustic transfer function (ATF) of SUBOFF submarine is established by using the propeller unsteady exciting force as an input, and the outer wet-surface vibration and radiated noise of the propeller, hull and whole submarine as outputs accordingly. The three ATFs of above-mentioned wet-surfaces are compared in accordance with spectral peaks and the propeller's modal frequencies as well as the modal shapes, the effect analysis of propeller blades' vibration on the structural vibration and acoustic radiation under vertical excitation is highlighted.

  Results  The results show that the effect of the propeller on the vibration and acoustic radiation of the whole submarine is mainly related to the propeller blades' modal frequencies and the single blade cross-vibration modes. The frequency response curves of the mean-square normal velocity level and the radiated acoustic power of the propeller's wet-surface will be plumped up at the single blade cross-vibration modes' frequencies, and so do curves of full submarine's wet-surface, but those of the hull's wet-surface are quite the contrary. At other frequency bands, the ATF of the hull's wet-surface can reflect the whole submarine's vibration and acoustic radiation characteristics.

  Conclusions  These results can serve as a reference for the acoustic design of submarine propellers, and also offer new insight into the analysis and identification of noise sources.