Research On Automatic Optimization Design Method Of Parametric Ship Model Aimed At Minimum Resistance

With the increasing attention of marine environmental protection,various countries and organizations around the world have introduced and implemented various rigorous rules for the fuel economy and energy efficiency design index of the shipping industry during the navigation process.This makes the minimum resistance ship form optimization design,which has always been an eternal topic in the shipping industry,become more and more important.At the same time,due to the complexity of ship hull resistance optimization design in new ship type acquisition,resistance prediction,restraint control,etc.,ship design workers in various countries are constantly exploring new methods that are faster,smarter and more efficient in ship optimization design.Therefore,this paper carries out analysis and research on automatic optimization design method of parametric ship model aimed at minimum resistance.In the process of hull optimization design,the ship automatic optimization system is established.The key issues such as ship model establishment,optimization method and optimization path in the parametric hull optimization design are discussed and analyzed.The main contents are as follows:First of all,this paper proposes an integrated optimization system based on parametric ship model.Based on the automatic optimization design of the ship model,the system provides various options in each stage of the hull optimization process,such as various optimization target selection,different optimization method selection and various constraint control options.Through the organic combination of various options in different optimization stages,the entire hull optimization design system becomes more convenient and intelligent,which improves the diversity and applicability of the hull optimization design,and also greatly improves the hull optimization design efficiency.Secondly,in the aspect of parametric ship model establishment,this paper proposes a ship parameter layered model,and based on this model,discusses the fully-parametric modeling and partially-parametric modeling method.At the same time,after the initial ship model is established,the designer often needs to adjust the ship model for the displacement and the position of the floating center.This paper also proposes a ship model transformation method based on the design target parameters.Finally,aiming at the defect that there are many characteristic parameters in the process of parametric ship model building and that parametric ship model cannot adjust the local ship form arbitrarily,two parametric-based ship optimization design paths are proposed in this paper.The first method is a hull optimization design method based on parameter sensitivity analysis.Before optimizing a common ship,the sensitivity analysis of the characteristic parameters in the modeling is performed to eliminate the parameters that have no significant influence on the ship resistance.Then the optimization design of the ship based on SOBOL algorithm and TSM(Tangent Search Method)optimization algorithm is carried out.The second is a combination of fully-parametric and partially-parametric ship hull optimization methods.Firstly,the NSGAII(Non-dominated Sorting Genetic Algorithm)optimization algorithm is used to optimize the design of the bow,stern and strut of a fully-parametric SWAHT(Small Waterplane Area Twinhull Ship).Then,based on the pre-optimized ship model,the partially-parametric ship modelling method is used to geometrically reconstruct the ship model to obtain the new ship hulls,and the final optimized ship model is obtained by the NSGA-II optimization method.In general,this paper takes the automatic optimization design method of parametric ship model aimed at minimum resistance as the main research content.The establishment method of fully-parametric ship model and partially-parametric ship model,the establishment method of ship automatic optimization design system and two optimization design methods based on parametric ship model are given.It helps subsequent ship designers to design ships with less resistance,while also making ship optimization design smarter and more efficient.