Study On Mechanism And Control Of Submerged Structure Vibration And Sound Radiation Excited By Longitudinal Force

The study on submerged structure vibration and sound radiation is received moreattention now. These studies focus on mechanical noise and fluid dynamical noise. Theproblem about the structure vibration and sound radiation caused by propeller force whichtransferred from shafting and bearing to structure is less studied. The submerged structurenoise will be more decreased by such problem solved.The mechanism of the propeller-shafting-hull system vibration and sound radiationcaused by propeller force is studied in this paper. The characteristic of structure vibration andradiation noise is analyzed. The method of structure longitudinal vibration control and thevalidity are calculated.The classic simplified submerged structure calculating model is built. The vibration andsound radiation characteristics of submerged structure excited by longitudinal force areanalyzed by FEM/BEM. The characteristics of the vibration and sound radiation excited byaxial symmetrical force are control by the longitudinal accordion modes. The characteristicsof the low frequency vibration and noise radiation excited by axial asymmetrical force aresame as the symmetrical force, but the high frequency vibration and noise radiation iscontrolled by the bending moment, and release more energy.The propeller and shafting are imported into the simplified submerged structure model.The characteristics of the propeller-shafting-hull system coupling vibration and soundradiation are studied. The change permanents of the propeller longitudinal forcetransmissibility and structure vibration and sound radiation are analyzed by using longitudinalabsorber. The effect of reducing the vibration and sound radiation by using longitudinalabsorber is verified in this paper.