Vibro-acoustic responses of a hull due to structural and acoustic excitations from a propeller

The vibro-acoustic responses of a submerged hull under propeller force are investigated. The propeller force is generated by propeller vibration and transmitted from the propeller to the hull via the shaft and fluid, namely, the structural and acoustic excitations from the propeller. Evaluating the effect of each excitation on the hull is important for the noise control of a vessel. This paper presents a technique using the finite element method and the coupling method based on the frequency response function to model a complex vessel comprising a threedimensional propeller, shaft, and hull, to separate structural and acoustic excitations from the propeller and to load the hull. The results show that the structural excitation from the propeller is the primary way to excite the hull. When a hull is subjected to structural and acoustic excitations simultaneously, the phase difference between the sound radiation from the hull due to structural excitation and that due to acoustic excitation determine whether the sound radiation from the hull increases or decreases. In general, the phase difference is in-phase for longitudinal cases and out-of-phase for transverse cases.