Dynamic performance simulation of a naval propulsion system

Abstract: A comprehensive approach to simulate the propulsion system behaviour of a ship during transients and off design conditions is presented in the paper. The system behaviour is described by a numerical model, developed in MATLABSIMULINK ® environment, already tested and validated with reference to different ship types and operating situations. The model may be simply adapted to different applications because of its modular architecture, allowing an extremely easy and gradual growth in complexity, for instance including accurate (thermodynamic) engine modules and ship manoeuvrability modules. A library of ‘blocks’ already available is used to represent the propulsion plant elements (engine, governor, gear, shaftline, propeller, hull, etc.) with a different degree of accuracy in relation to the concerned application. The system of algebraic and differential equations linking together the selected modules and representing the propulsion system mathematical model, is solved in the time domain by means of different available MATLAB® solvers. The application presented in this paper concerns a small naval vessel, a corvette of 1500 tons displacement, whose propulsion plant consists of a twin shaft arrangement with controllable pitch propellers. Each shaft is driven, through reduction gears, by a sequentially-turbocharged medium speed diesel engine. The presented model has been validated by comparing the simulation results with steady state manufacturer experimental data, for the diesel engine, and with ‘ad-hoc’ full scale measurements of propulsion plant and ship parameters, relative to off-design and transient operating conditions.