Performance Decay Analysis of a Marine Gas Turbine Propulsion System

Marine propulsion plants are designed to be more and more efficient to minimize fuel consumption and pollution emissions. However, during the ship operating life, propulsion components and hull are characterized by a certain performance decay, responsible for a worse behavior of the overall propulsion plant. For this reason, the several propulsion components are periodically subjected to expensive maintenance works to restore, as far as possible, their original design characteristics. In the present study, the propulsive performance variation of a naval vessel, powered by a gas turbine as part of an innovative CODLAG system, is simulated and analyzed by means of a detailed and validated numerical code. A sensitivity analysis regarding the influence of the main components deterioration (gas turbine, propellers, and ship hull) on the overall behavior of the propulsion plant is carried out. Several speed profiles of the vessel have been analyzed in terms of the usual performance parameters (ship speed, engine power, and fuel consumption) as well as the pollution emissions of the gas turbine. The main aim of the work is to get useful information for the ship management and maintenance scheduling (condition-based maintenance).