Coupled vibration characteristics of a submarine propeller-shaft-hull system at low frequency

Hongxing Hua,Yong Chen,Feng Chen

doi:10.1177/1461348419846722

Abstract

The coupled longitudinal and transverse vibration characteristics of a submarine propeller-shaft-hull system at low frequency are studied in this paper. Two substructures, which are the propeller-shaft subsystem and the submarine hull, are first modelled using the finite element method. The two substructures are then connected through bearings, which are simplified as longitudinal and lateral springs and dampers. The modes, the natural frequencies and the coupled vibration characteristics of the two substructures and their synthesized system are simulated. An experiment studying the dynamic characteristics of a large-scale submarine test-rig is proceeded and compared with the numerical results, showing great consistency. Finally, transfer path analysis of the low frequency excitation forces using power flow method is discussed.

Highlights

Low-frequency vibration of a submarine is one key factor restricting its stealth performance
This paper studies the coupled transverse and longitudinal vibrations of a submarine propeller-shaft-hull system using the finite element method (FEM)
The simulated frequencies at which peaks in the response amplitude occur of the propeller-shaft, the hull and the propeller-shaft-hull system using FEM are very close to the experimental results

Summary

Introduction

Low-frequency vibration of a submarine is one key factor restricting its stealth performance. The excitation forces of the rotating propeller-shaft system, such as the residual unbalance of the propeller, the misalignment of the shafts and the fluid-induced forces acting on the propeller, will be amplified in the process of transmission from the propeller to the hull, because of the elasticity of propeller and shafting These forces are one of the most important sources causing low-frequency vibrations of the submarine. The elasticity of the propeller has great inference on the force transfer characteristics and noise radiation of the hull.[1] Merz et al.[2] studied the structural and acoustic responses of a submarine hull due to propeller forces He considered the propeller as a modal mass-stiffness system attached to the shaft, and he only implemented the first-order natural frequency of the propeller in the model by neglecting the coupling between the propeller and the shaft.

Objectives

Results

Conclusion