Large-Scale Merchant Ship’s Maneuverability And Main Engine Power Evaluation Considering The Matching Process Of Ship,Engine And Propeller

Large merchant ships have played an important role in ocean shipping and world trade,but their ship type and displacement also lead to greater navigation resistance,poor heading stability and slower maneuvering response in severe sea conditions.Therefore,the study of maneuverability of large commercial ships are beneficial to improving their navigation performance.The main engine is the source of the ship’s navigational power.The maneuverability of the ship is not only affected by its own ship type,but also by the output performance of the main engine.Therefore,considering the dynamic performance of the main engine when studying the navigation performance of large commercial ships can bring the more consistent results with the real situation.First,the KVLCC2 main engine power is calculated according to the naval coefficient method and the EEDI minimum propulsion power criterion,and then the Fortran language is used to establish the steady-state model of 7G80ME-C9.5 diesel engine in-cylinder process.The interpolation method is used to calculate the output power of the main engine under any working conditions.The three-dimensional model of crankshaft,transmission shaft and propeller is modeled by Solidworks,by which the moment of inertia of the ship’s shafting system is obtained.A governor model is established based on the PI control algorithm.The calm water resistance coefficient of the KVLCC2 at full scale is calculated according to the Froude-Similarity method.The dynamic matching process of the ship,main engine and propeller is established according to the MMG maneuverability model and the dynamic model of the main engine.Based on the dynamic model of the ship,main engine and propeller,the moving forward and turning ability for the full scale KVLCC2 at calm water were simulated.The navigation characteristics of the ship and the load characteristics of the main engine under various conditions were analyzed.The simulation results were compared with the calculation results of the MMG model without considering the main engine.It is shown that the main engine will be seriously overloaded if the ship is starting from zero forward at a constant high propeller rotation speed or is making constant turning at the initial high forward speed.A reasonable main engine rotation speed control strategy can avoid the overloaded operation of the main engine.The results also demonstrate that the dynamic model of the ship,main machine and propeller could properly simulate the ship maneuverability performance,which provides a valuable tool for the ship’s main engine control strategy and the determination of the ship installed power.