The random vibration and force transmission characteristics of the elastic propeller-shafting system induced by inflow turbulence

Abstract

Random vibration and force transmission characteristics of an elastic propeller-shafting system induced by the inflow turbulence are analytically studied. Both the propeller blades and the shafting are simplified as three-dimensional elastic beam, which are connected by lumped spring elements. Based on the Timoshenko beam theory, an analytical model considering both the longitudinal and transverse responses of the propeller-shafting system is developed. The random pressure spectrum induced by inflow turbulence is computed by the correlation method and is mapped onto the blades as exciting source. By virtue of the frequency response function matrix, the random vibration characteristics of the propeller-shafting system and forces transmitted through different bearings are obtained. Analytical results show that the elasticity of the propeller blades cannot be neglected and the bending modes of the propeller blades amplify both the longitudinal and transverse transmitted forces. The longitudinal force transmission is mainly controlled by the propeller elasticity and the longitudinal stiffness of the thrust bearing, while the frequency and magnitude of the transverse force is mainly controlled by the bending modes of the shafting and the system elasticity, respectively.