Evaluation of Torsional Vibration Characteristics of Ship Propeller-Engine Shaft System Based on Theoretical Sensitivity Analysis

Abstract

In recent years, the reduction of CO2 emissions from transport equipment has been required. Even in marine engines, energy saving measures such as longer stroke (lower engine speed), maximum pressure in the cylinder, and electronic control have been taken. However, these measures generally tend to increase the engine excitation force, and increase in torsional vibration is a problem in propeller propulsion shaft systems. In this paper, a simplified mathematical model was derived for the torsional vibration caused by engine torque harmonics in the propeller-engine propulsion shaft system of a ship. By performing theoretical sensitivity analysis using this model, the effects of engine inertia moment adjustment with a tuning wheel and intermediate-shaft stiffness adjustment used as a measure to reduce torsional stress at torsional resonance are clarified. Moreover, the sensitivity equation obtained was compared with the numerical analysis results to verify that it had sufficient accuracy.