Research On Optimal Design Method Of Hull Form Based On Wave-making Resistance

In recent years,proposed "Green Ships" and "Industrial Manufacturing 4.0",the requirements of green shipping and intelligent design and manufacturing make researchers have great interest in hull line design.At present,CASES commercial software and self-developed integrated system of scientific research institutions are widely used to optimize the hull line design of conventional ships.Hull form optimization is a comprehensive subject.In this paper,the hull form reconstruction and deformation technology,wave resistance prediction technology,optimization technology and approximation technology are orderly integrated to form a hull form optimization design system.Through the realization,verification and application of the theoretical methods of each module,with the goal of wave-making resistance,an efficient,fast and intelligent hull form optimization design method is discussed,and Wigley and KCS hull forms are optimized.In this paper,a reverse algorithm of control points(control network)of NURBS curve(surface)is applied to geometric reconstruction from the beginning of hull form optimization.The functions of hull surface deformation,surface splicing,surface segmentation and local area encryption are realized without the initial condition of hull tangent vector.The mathematical models and basic principles of TM method,RBF method and FFD method are introduced in detail.Through the application of examples,the TM method has less design variables and is easy to realize,which is suitable for the overall deformation of hull form.RBF method and FFD method have many design variables and flexible deformation mode,which are suitable for local deformation of hull form.Then,a program based on Hess Smith panel method is compiled to calculate the potential flow around an arbitrary three-dimensional body.The reliability of the program is verified by taking the sphere and ellipsoid as examples.At the same time,based on the panel method,the calculation program of wave-making resistance of hull based on Dawson method is compiled,and the reliability of the prediction method is verified by Wigley and KCS hull form.Considering that the hull form optimization system needs a lot of calculation in the iterative process,the C++ AMP parallel technology is used in the Dawson method.Through the calculation and analysis,this technology can greatly improve the calculation efficiency of hull wave resistance prediction.Secondly,four intelligent optimization algorithms(GA,PSO,CSA and ISA)are implemented.From the perspective of hull form optimization,the function test set and performance evaluation index of algorithm simulation experiment are designed.Through the analysis of simulation results,the theoretical effectiveness of the four heuristic algorithms in the optimization problem is verified,which provides theoretical methods and effective technical support for the optimization module of hull form optimization design system.Then,a high-precision approximate model based on SLE-BP neural network was established,and the reliability of the program was verified by the use of the Wigley ship design.The approximate model obtained by training,through simulation experiment analysis,is able to realize the prediction of wave making resistance with higher accuracy.In the practical application of hull form optimization,this method is applied to the calculation of wave-making resistance of a large number of hull form sample sets,which has a certain effect of improving the optimization calculation.Finally,the Wigley and KCS hull form are optimized,and the CFD method considering viscosity is used to calculate the total resistance change of the ship before and after the optimization,which verifies the applicability of the hull optimization design method based on wave resistance constructed in this paper.From the analysis of Wigley and KCS hull form optimization results,the free surface wave height distribution and hull surface pressure of optimized hull form are improved obviously.At a certain speed,the wave making resistance of Wigley hull form is reduced by 9.1%,and that of KCS hull form is reduced by 18.95%.