Energy Saving In Various Trim Conditions For Ship Based On CFD Theory

The analysis,evaluation and optimization of ship energy efficiency is one of the core parts of intelligent ship energy efficiency and the core method of improving energy efficiency.The trim optimization energy saving technology is one of the core contents of the research on the analysis,evaluation and optimization of ship energy efficiency,it can effectively improve the traditional and extensive navigation floating state management and provide an important reference for the realization of green intelligent decision-making and fine management of ships,therefore,it is of great significance for the research on this technology.The key to the trim optimization technology is to build the real ship resistance and power database and the correct optimization algorithm under different floating conditions.In this paper,a 300,000 tons Very Large Ore Carrier is selected as the target ship.Firstly,by consulting relevant literature,this paper determines to select ANSYS Fluent for the numerical simulation calculation,and introduces the theoretical knowledge of the trim optimization energy saving technology,the mathematical model of CFD simulation and the support vector machine algorithm.Secondly,Maxsurf software was used to build a 3d model of the target ship,and a numerical tank of the target ship was built in Fluent to obtain the hydrostatic resistance of the target ship,the accuracy of the resistance model was verified by comparing the results of ship model experiments,indicating the feasibility of this method for resistance prediction.The same method is used to calculate the resistance of ship model under different trim floating states,and the law of resistance is analyzed to prove that the trim optimization technology has great potential in energy saving.In order to further quantify the energy saving effect of the trim optimization technology,the ship model resistance at different speed and trim under the condition of full load is solved,and the real ship resistance at different speed and trim is obtained through the conversion of real ship resistance using the three-dimension method.In order to further quantify the energy saving potential of the trim optimization technology,the ship model resistance under different sailing speeds and trim floating states was solved by taking full load condition as an example,and the static water resistance of the target ship under different sailing speeds and trim floating states was obtained through the conversion of real ship resistance using the three-dimensional method.By analyzing the open water characteristic of propeller and the matching relation between propeller and propeller,the resistance and power database under different speed and trim is obtained.Finally,trim optimization model is established and solved by SVM algorithm.To test and verify the aecuraey of the model,and through analyzed historieal operating data aecuracy verification of the model,and the energy saving effect of trim optimization technology calculation,the calculation results show that the model error is within 5%,meet the precision requirement in engineering,relative to the draft state,when the ship sailing on the optimum angle of trim with 6%-7%of the energy saving potential.