Propeller - diesel engine interaction in a turn

In this paper the simulation results of a ship mobility model are presented. This model consists of an elaborate propulsion model (diesel engine, shaft, propellers), a modified propeller model and a ship manoeuvring model (hydrodynamic forces, ship standard manoeuvres). The objectives are to investigate the interaction between the diesel engines and the propellers in a turn and to explore the value of a mean value diesel engine model. The results are compared with the results of the validated manoeuvring model ‘FreSim’. This model does not have a sophisticated diesel engine sub-model but a simple constant torque propulsion engine.
From the simulation results, three conclusions can be drawn. Firstly, the elaborate diesel engine model calculates the engine torque in such a way that the manoeuvring results (ship speed, rate of advance etc) are comparable with the validated FreSim results. Secondly, apart from engine torque, the diesel engine model also calculates other values such as exhaust gas temperature. This exhaust gas temperature can reach unexpected high values in a turn. Finally, in a twin-shaft configuration, the inner and outer propellers are loaded differently because of differences in wake. This results in difference in loading and exhaust gas temperature of the diesel engines.