Study On The Output Fluctuation Characteristics Of Main Engine Of Sail-assisted Ships

With the development of the world economy, the problem of the oil shortage becomes serious day by day. The ship operation cost has increased a lot because of the high fossil oil prices which result from the unbalance of supply and demand caused by the oil shortage. At the same time, environment problem has come into notice for more and more people, thus International Maritime Organization (IMO) has attach great concern to how to increase oil combustion efficiency and reduce emission. With the new regulations been released, shipping business all over the world is challenged by the high fossil oil price and environment protection, faced with huge pressure of energy saving and pollutant reduction. Few spaces of energy saving and pollutant reduction are left for ship diesel engine, so further steps are subjected to the technical progress or the new technology.Under above background, the application of sails thrust as the auxiliary power for ships regain people's attention. But because of the continuous changing of wind field in nature, the thrust of sails changes in value and direction which will cause the fluctuation of power plant's output power, and its influence is vital in certain situation, it's necessary to study the influence of sail thrust fluctuation to diesel engine.At the beginning, sail thrust fluctuating graph is established based on the ship typical operating mode at typical route thesis, then characteristics of ship propeller, ship resistance and diesel engine are introduced respectively, based on which the mathematical model of ship-engine-propeller-sail system is established. Secondly, the dynamic simulation model of overall system is constructed by utilizing simulation software MATLAB/Simulink combined with the former mathematical model. Thirdly, the input signal of simulation model is obtained on the basis of sail thrust fluctuating graph, and then diesel engine output power curves under different operating condition are obtained by simulation. At last, conclusions are made by comparing the different output power curve of diesel engine. This thesis focuses on the study of diesel engine output power fluctuation caused by changes of sail thrust. The mathematical model of ship-engine-propeller-sail system and its computational simulation model of are established, and the fluctuation curves of engine output power under some operating mode is obtained which is the foundation of the study of coupling characteristic of Wind-Diesel propulsion plant, and it is of great significance for sail-assisted ship to enhance the reliability and service time.