Research On Boundary Layer Mesh Generation Technology For Complex Geometric Features Of Aircraft

In the context of the rapid development of computer technology,Computational Fluid Dynamics(CFD)is playing an increasingly important role in engineering and technology fields such as aerodynamic layout design of aircraft and UAV design.Before CFD can be applied to the numerical analysis of these engineering problems,the continuous computational domain of the problem needs to be discretized into a number of basic cells,i.e.,mesh generation.Boundary layer mesh generation is a critical step in mesh generation,and a high-quality boundary layer mesh ensures the accuracy of the numerical simulation.At present,it is still very difficult to generate high quality trigonal mesh cells in the boundary layer of complex geometrical features.Therefore,this article focuses on researching the boundary layer mesh generation algorithm for complex geometric features of aircraft.Based on the idea of a constraint framework,a class of algorithms that first generates a constraint framework and then generates the boundary layer mesh under the constraint of the framework is developed.In addition,local mesh quality optimization is combined with the geometric features of the surface mesh,ensuring the quality of the boundary layer mesh at complex geometric features.The research work of this article includes the following:(1)Boundary layer meshes are generated based on the idea of constrained frame construction.Firstly,by calculating the tensor voting matrix of the grid points and the flatness signal values of the grid cells,feature lines,feature cells and flat cells are extracted and used to partition the surface grid into regions using a simple growth algorithm;then,on the basis of the surface grid partition,the boundary points of the sub-surface grid are extracted,fitted using the least squares method,and then linearly transformed to lift to the top position of the boundary layer A constraint frame is generated;then,a radial basis function is used to interpolate the internal grid points using the constraint frame points as the base points,and the generated grid points are connected according to the topological relationships to generate the top-level grid,and finally the trigonometric grid cells are filled according to the set parameters.(2)An algorithm is designed to optimize the quality of the boundary layer mesh in conjunction with the feature recognition of the surface mesh.Firstly,the intersection of the meshes around the feature lines is judged;then,the intersection is optimized by using a reduction strategy and adding constraints to advance the position;finally,the constrained normal direction is optimized by adjusting the meshes around the feature cells.(3)The boundary layer mesh generation algorithm of this article is integrated into the NNWGrid Star unstructured mesh version and seamlessly integrated with the surface mesh and spatial mesh generation programs developed by the software.This constitutes a complete hybrid mesh generation process.In order to verify the quality of the mesh generated by this article’s method,a complex-shaped aircraft is used to generate hybrid mesh using both this method and the commercial software Pointwise,and numerical calculations are performed on both.The comparison of the numerical results shows the effectiveness and correctness of this article’s method.