The temperature and especially the pressure (responsible for the torque development of the engine) diagrams obtained from the engine model match well with the respective diagrams provided by the engine manufacturer.

　

Fig. 10: Temperature versus crank angle a as calculated from the model T_sim, and the measured data T_mes as provided from the engine manufacturer.

Fig. 11: Absolute pressure versus crank angle a as calculated from the model p_sim, and the measured data p_mes as provided from the engine manufacturer.

　

3.2 Dynamic Results

Here the results for the complete system of the engine-ship model, obtained from a simulation run for 600. s are presented. The initial ship velocity is set equal to 10.8 m s^-1. The engine's initial angular velocity was set at a = 95. rpm. The rudder is set first to δ = O. then at t = 60. s is deflected to δ = 15, deg assuming a deflection speed of δ = 6. deg s^-1 then at t = 240. s is again deflected to δ = -15 deg assuming again the same deflection speed for the rudder.

In Fig. 12 the ship's path is illustrated. As expected at the beginning the ship is moving in straight line until at t = 60. s, when the rudder is deflected to δ = 15. deg, which results to right turn for the ship. Accordingly at t = 240. s the rudder is deflected to δ = -15 deg, which results to left turn for the ship. As expected the radius of the first turn is greater than the second one since the velocity of the ship is decreased due to the ship turning.

　

4. CONCLUSION

　

In this paper a method for modeling marine propulsion systems using a scalable and extendable building block approach with a well defined interface between the modeled subsystems was presented. Various extensions to the proposed method are possible. The method is easily extendable on the interface level, the element level and the mathematical model level.

Possible extension is the introduction of new elements to the various element groups. For example waterjet, bow thruster and roll motion stabilizers elements can be introduced to the ship group of elements, Wankel and free piston elements can be introduced to the geometry group of elements, 1-D open thermodynamic elements can be introduced to the fluid group etc. Possible extension is also the introduction of new groups of elements (which requires the introduction of new types of interfaces). For example an electrical group of elements can be introduced for modeling the electric power distribution (possible elements belonging to this group can be generators, motors, transmission lines etc), enabling the modeling of electric propulsion and machinery. Also a hydraulic group of elements can be introduced enabling the modeling of hydraulic equipment (such as pumps).

　

Fig. 12: Ship's path.

　

References

　

[1] Heywood J.B., Internal Combustion Engine Fundamentals, McGraw-Hill, ISBN 0-07-100499-8, 1988

[2] Larmi M., Transient Response Model of Low-Speed Diesel Engine in Ice-Breaking Cargo Vessels, Ph.D. Thesis, Acta Polytechnica Scandinavica, Helsinki, Finland, ISBN 951-666-378-8, 1993

[3] Ciulli E., A Review of Internal Combustion Engine Losses. Part1: Specific Studies on the Motion of Pistons. Valves and Bearings., IMechE Paper 0954-4070, 1992

[4] Winterbone D.E., Tennant D.W.H., The Variation of Friction and Combustion Rates During Diesel Engine Transients, SAE Paper 810339, 1981

[5] Millington B.W., Hartles, E.R., Frictional Losses in Diesel Engines, SAE Paper 680590, 1968

[6] Holman J.P., Heat Transfer, McGraw-Hill, ISBN 0-07-029618-9, 1981

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