Numerical analysis on dynamic behaviors of coupled propeller-shafting system of underwater vehicles

Abstract

The control of unsteady bearing forces generated by propellers is of great importance for the reduction of vibration and noise of underwater vehicles. This paper is concerned with the development of a numerical method for analyzing the hydroelastic behaviors of fully coupled marine propeller and shafting system immersed in water. A three-dimensional panel method for fluid modeling combined with a finite element method for modeling of the shafting system is developed. The two sets of equations of the structural system and the fluid are strongly coupled by considering the non-penetration boundary condition on the wet surface of the propeller. A modal reduction technique is employed to determine the hydroelastic responses of the coupled fluid-propeller-shafting system, which overcomes the low numerical efficiency of the method due to the asymmetric added matrices of the propeller. The validity of the proposed method is confirmed by comparing the present results with those solutions obtained from finite element analysis. It is found that for the case of the driving force frequency close to the umbrella mode frequencies of the propeller and longitudinal mode frequenices of the shaft, the coupling of the fluid, propeller, and the shaft must be taken into account for predicting the dynamic response of the system.