A Modelling Approach for the Overall Ship Propulsion Plant Simulation G. P. Theotokatos Shipbuilding Department, School of Technological Applications TEI of Athens St. Spyridonos Str., 12210 Egaleo GREECE Abstract: - In the present paper, a modelling approach for the simulation of the overall ship propulsion plant is presented. A cycle mean value model with differential equations for the calculation of the engine crankshaft and turbocharger shaft speeds is used for the modelling of the main engine of the vessel. The ship shafting system is modelled using the power balance and its efficiency. In order to calculate the propeller thrust and torque, the polynomials for the propellers of the Wageningen B type are used. In addition, the ship velocity and the movement along its longitudinal axis are also calculated using the differential equation describing the ship surge dynamics. The mathematical equations of the ship propulsion plant model are implemented and solved using the computational environment MATLAB Simulink®. The model was used for the simulation of the propulsion plant of a merchant ship under various operating conditions and the derived results are presented. Key-Words: - ship propulsion plant, marine Diesel engine, simulation, MATLAB Simulink® 1 Introduction Nowadays, simulation of the various components of the ship propulsion plant plays important role on the better understanding of the physical processes occurring, as well as the interaction between the involved subsystems. In addition, simulation can be used to facilitate the development and optimization procedure of the ship powerplant components by initially testing alternative design options, or to evaluate propulsion plant subsystems control schemes. The simulation tools used throughout the design procedure of the propulsion plant subsystems can be of varying complexity. Cycle mean value models are used for fast transient powerplant performance estimation, evaluation of the interaction between the involved components as well as for the engine control system development [1,2]. Zero-dimensional and one-dimensional models are used for more detailed modelling of the thermodynamic and flow dynamic processes inside the engine components [3- 5]. Three-dimensional (CFD or finite elements) models [6] are used for the development, investigation or optimization of powerplant components design where the evolved processes take place in three dimensions (e.g. engine combustion chamber design, propeller design, etc.). The objective of this work is to present a comprehensive but easily handled tool for the simulation of the overall ship propulsion plant, so that the initial tests of various design options, the interaction between the various components and control scenarios for the main engine as well as propeller pitch control can be investigated. In that respect, the mathematical modelling of the overall ship propulsion system implemented in the computational environment MATLAB Simulink® is accomplished. The main engine of the ship is modelled using a cycle mean value model approach in conjunction with differential equations for the calculation of the engine crankshaft speed and the turbocharger shaft speed. The thermodynamic and flow dynamic processes in the engine components are taken into consideration in order for the various engine parameters to be calculated. The angular momentum conservation and the energy balance in the propulsion plant shafting system in combination with the shafting system efficiency is also taken into account for calculating the engine shaft speed. The polynomials for the Wageningen B propeller type are used for the calculation of the propeller toque and thrust. The differential equation derived using the ship surge dynamics is used for calculating the ship longitudinal movement and velocity. The developed tool was applied for the simulation of the propulsion plant of a merchant ship and the derived ship and propulsion plant operating parameters are presented. 6th WSEAS International Conference on SYSTEM SCIENCE and SIMULATION in ENGINEERING, Venice, Italy, November 21-23, 2007 80