飞行器RCS计算前置处理中裁剪曲面剖分算法

Algorithm of trimmed surface triangulation of prepositive disposal in predicting RCS of aircraft

在雷达散射截面(RCS)计算中,首先需要将物体的表面进行三角剖分,称为前置处理,三角片单元的边长通常为0.1个波长(一般1个波长取3 cm).飞行器外表形状复杂,在建立数学化模型中,使用了大量的裁剪曲面,曲面之间的关系非常复杂,而3 mm边长的三角片剖分,使得飞行器的三角片单元的数目巨大,给前置处理带来难度.对此,提出了一种裁剪曲面三角网格剖分的方法.利用飞行器外形设计的特点,在以拱高为逼近误差的前提下,把曲面离散一系列等参数线,等参数线上等弦长布点,两两参数值相邻的参数线生成网格单元.根据网格单元与裁剪区域的位置关系,将落在裁剪区域外的网格单元进行裁剪处理.然后对曲面间边界处的网格进行相容性处理,最终实现多张裁剪曲面的三角网格剖分.

While computing radar cross section （RCS）, surfaces of objects were primarily triangulated, which was called prepositive disposal. The length of the edge of the triangle was generally O. 1 wavelength（in general one wavelength is 3 cm）.The shape of aircrafts was complex , aircrafts＇ geometric model contained many trimmed surfaces, the relationship between trimmed surfaces was complex. Meanwhile surfaces were triangulated into many triangles with the edge of 3 mm, therefore the number of triangles was huge. All these resulted in difficulties in the prepositive disposal. An algorithm of trimmed surfaces triangulation was put forward. Using the characteristic of aircraft model and satisfying the approach error the surface was dispersed by isoparametric curves, the curves were dispersed into points at the given length and the meshes were composed of points on two adjacent isoparameteric curves. According to the position relation of meshes and the trimmed area meshes which were out of the trimmed atea were trimmed. Then meshes on the surfaces boundaries were converted into being consistent. Triangulation of trimmed surfaces can be realized.