Research On Parametric Method Of Aircraft Shape And Development Of Visual System

In the current complex international situation,the development of a country in the field of aerospace has increasingly become a symbol of whether it is a powerful country.With the continuous exploration and development of the country in the field of aerospace,aircraft design is getting more and more attention in the field of national defense industry.Aircraft shape design is one of the important modules in the whole design process,and its excellent degree will directly affect the maneuverability,stealth and other performance of the aircraft.The aircraft shape design is based on the aircraft flow field data obtained from the aerodynamic analysis,and uses the shape parameterization algorithm to generate the three-dimensional model of the aircraft.In the process,it usually needs to be revised repeatedly,and the generated model surface is required to be smooth,which can accurately describe the local details.The quality of the work directly affects the progress of the overall project.Therefore,it is of practical engineering significance to study the algorithm of fast and accurate generation of aircraft 3D shape model and display it accurately and completely.Compared with other shape parameterization methods,CST parameterization algorithm has the advantages of less design variables,adjustable,high precision,wide design space,smooth geometry,and better robustness.B-spline combined with CST parameterization method can enhance the ability to describe the local geometric characteristics of the shape.However,because the basic function of B-spline is a subsection function,it can not be expressed uniformly by analytical formula,and its calculation amount will increase sharply with the increase of order.In view of the disadvantages of B-spline in high-order calculation,the research work of this paper is as follows:(1)Compared with other methods,the CST parameterization method has the advantages of fewer design variables,adjustable,high precision,wide design space,smooth geometric shape and better robustness,and is widely used in the design of aircraft shape parameterization.Because the Bezier polynomial has insufficient ability to describe local geometrical characteristics,some scholars have published an improved method to construct the shape function by replacing the Bezier polynomial with the base function of B-spline,in order to enhance the local description ability of the CST parameterization method to the shape.Because the B-spline method has good effect on the fitting,smoothing and interpolation of the data,the method does play an optimization role when the order is small.However,the base function of B-spline is a segmented function,so the analytic formula can not be used for uniform expression,usually most of the use of iterative method evaluation,one drawback of this method is that there will be multiple repeat calculations,as the order increases,the amount of computation also increases dramatically.One disadvantage of this method is that repeated calculation will occur for many times,and the amount of calculation will increase sharply with the increase of the order.For B-spline in high order number the shortcoming of large amount of calculation,this paper puts forward using B-spline basis function based on vector extension to improve shape category function method.This B-spline function based on vector expansion is implemented in CST parameterization method in place of Bezier polynomials to improve the optimization design efficiency of airfoil and increase the parametric design space.The computational efficiency of K order B spline nonzero value has been increased by 2k+1 times.(2)An accurate,efficient,real-time and online interactive visual system of aircraft shape is designed and implemented.The system integrates the parameterization algorithm of common aircraft shape,which can dynamically generate three-dimensional aircraft shape according to the parameters configured by users and the selected algorithm,and can display the 3D effect in real time.At the same time,it supports the generation,storage,import and export functions of aircraft model data so as to manage and reuse the data.