Research On The Energy-Saving Optimization Of Ship Formation Based On CFD

In recent years,with the rapid development of the global economy,the mutual trade between different regions is becoming more and more frequent,and the shipping industry plays an important role.In order to improve the hydrodynamic performance of a ship,a good hull line is necessary from the perspective of economic performance and resource saving.In addition,due to the huge volume of cargo and the time limit of cargo task,single ship cargo transportation has not been able to solve the huge trade demand of customers,and the formation navigation of ships has been paid more and more attention to and applied to the actual transportation task.According to many natural phenomena such as flying geese in the South and flying fish,it can be seen that the group movement phenomenon has a low energy consumption arrangement,so The formation with high energy-saving rate also exists when the ships are sailing in formation.The optimal design of hull line is an essential part of ship design.The realization of the deformation of the three-dimensional hull surface becomes a key technical problem to be solved in the optimal design of hull lines.In this paper,a self fusion method,which is based on the basic theory of NURBS curve and surface,is used to modify the ship's three-dimensional surface.Through the fusion operation of the basic cross section 'of the mother ship,the basic cross section of the new ship's form is obtained,and the three-dimensional surface of the new ship's form is obtained by interpolation,so as to realize the deformation of the three-dimensional surface of the ship.Secondly,CFD(Computational Fluid Dynamics)technology,which has the characteristics of high prediction accuracy,short period and low cost,is used to predict the hydrodynamic performance of the new ship.Using the experimental design to give the sample points scientifically and effectively,combining the self fusion method and CFD technology to realize the simulation calculation of each group of sample points by building an automatic calculation platform,combining the numerical calculation results with the approximate model technology to build the polynomial response surface model(RSM model),and using the multi Island genetic algorithm to optimize the polynomial response surface model globally,to get the fixed speed The ship type with the least resistance when sailing directly.When a ship is sailing in a formation,due to the influence of the pilot ship on the surrounding flow field and the disturbance of the propeller operation on the wake flow field,the flow field around the follower ship will change,so that the body pressure of the follower ship will be redistributed,resulting in the change of the following ship's navigation resistance.This paper analyzes the resistance of each ship and the whole formation based on the causes of the ship's resistance Change the characteristics,explore the best formation of energy saving rate for each ship and the whole formation.First of all,we optimize the formation of the pilot follower double ship formation,use the volume force propeller instead of the real propeller to simulate the disturbance of the propeller operation on the ship's wake field,determine the optimization range of the pilot follower double ship formation according to the theory of the safe distance between ships and CFD technology,and divide the optimization range into the transverse and longitudinal areas,and use the multi Island genetic algorithm to carry out the optimization for each area respectively The optimization is to find the optimal formation of each ship and the whole formation in each region,and compare the optimization results of the two regions to determine the area with the best energy efficiency in the navigation of the ship formation.Then,according to the optimization of the navigation following the formation of two ships,the optimization is extended to the study of the formation of three ships,and the ships and the whole formation section are obtained when the three ships are sailing The formation with the best energy ratio provides the theoretical basis and technical support for the navigation of ship formation.