Routing Optimization Model And Intelligence Algorithm For Wind-assisted Ships

Aimed to the global important demand of energy-saving and emission reduction, and urgent need of transoceanic crossings to cut down fuel costs, this thesis, focusing on route optimization for wind-assisted ships, can provide theoretical basis and technical support in the hope that the ocean wind resources can be utilized effectively.According to the monthly mean grid data of a10-year record from UCAR, the distribution characteristics of ocean wind speeds and directions are analyzed, and it is found that the ocean wind speeds and directions always keep stability in5°or even larger sea areas, so that the ocean wind resources are available for wind-assisted ships. Based on the above conclusion, this thesis proposes a new idea that the wind-assisted ships can make maximum use of ocean wind as auxiliary thrust and finally achieve the energy-saving and shipping efficiency improvement through taking some suitable deviations on their original routes in the condition of global optimum, which is also called ship route optimization. Besides, according to the data structure of ocean wind field, this thesis proposes an algorithm that can extract the grid data around ship route effectively by calculating the index value of wind data, which provides a basic data support for the follow-up researches on ship route optimization.On the one hand, in the condition of fixed shipping date, reduce the main engine power as it does, a wind-assisted ship can keep her speed by the using of the auxiliary power that provided by ocean wind resource, and thus reduce her fuel consumption. Here takes the "minimum fuel consumption" as optimization object, the energy consumption calculation model and evaluation criteria for route optimization are modelled in the condition of fixed ship speed, and the route optimization model for "minimum fuel consumption under the limited of voyage time" is built finally. On the other hand, in the condition of fixed main engine power, due to auxiliary propelling of ocean winds, the wind-assisted ship may speed up so as to reduce the total voyage time. Here takes the "minimum voyage time" as optimization object, the ship speed calculation model and evaluation criteria for route optimization are modelled in the condition of fixed main engine power, and the route optimization model for "minimum voyage time" is built finally. At last, by considering the characteristics and computation scales of above two route optimization models, this thesis proposes an intelligence algorithm that can be used to solve them on the basis of simulated annealing, and a76,000DWT wind-assisted cargo ship is taken as the experimental ship by which the optimization models and their algorithm are simulated and verified. The simulations indicate that the fuel consumption can be reduced by11.22%at the cost of less than100minutes added in voyage time when the experimental ship sails on "minimum fuel consumption" route, and that when the experimental ship sails on "minimum voyage time" route, in comparison with sailing on the great circle without wind-assisted equipment, the voyage time can be reduced by nearly30hours, and the fuel consumption can also be saved by more than9%.In conclusion, the research result in this study can be applied to optimize the routes for such new ships named wind-assisted ships, and guide the modern ships to use the ocean wind rationally as an alternative auxiliary energy. Besides, it also has a significance of guidance for the further studies of wind-assisted equipment.