本文選題：快速射線追蹤算法 + 腔體電磁散射�。� 參考：《南京郵電大學》2017年碩士論文

【摘要】：隨著國家大力投入國產(chǎn)大飛機項目,大型飛機的散射特性的研究越來越重要。飛機的進氣口(腔體形狀)產(chǎn)生的散射是飛機散射的重要組成部分。傳統(tǒng)的低頻電磁數(shù)值計算方法雖然可以準確的求解目標物體的散射,但隨著尺寸增大會占用巨大的計算機資源且計算速度較慢。而高頻算法可以快速的求解,節(jié)約計算機資源,實現(xiàn)快速計算。本文對開口腔體結(jié)構(gòu)的散射的原理及計算進行了展開與討論。基于射線追蹤(Ray Tracing Algorithm)的彈跳射線算法(SBR)是計算腔體RCS的一種高頻方法,特點是物理概念簡單,易于編程實現(xiàn)。該算法是幾何光學(GO)與電磁場面等效原理的結(jié)合,能計算得到較精確結(jié)果。首先,本文分析射線追蹤的基本方法,從射線發(fā)射,路徑計算,以及射線接收都進行了詳細討論。傳統(tǒng)射線追蹤都無法避免大規(guī)模的線面求交運算,這部分運算耗時巨大。針對這一問題,本文采用了一種基于空間剖分射線追蹤算法。與傳統(tǒng)加速算法類似的都是對傳播空間進行分割。不同之處在于,新方法將傳播空間分割成若干個相互獨立的三角形單元(二維空間)或者四面體單元(三維空間),利用射線與剖分單元的幾何位置關(guān)系,快速計算射線傳播路徑,完全避免進行相交測試,很適合復雜環(huán)境條件下的射線傳播預測。其次,把基于空間剖分射線追蹤算法引入彈跳射線法(SBR)計算腔體散射的計算中。新射線追蹤算法可以快速跟蹤射線路徑和場強。同時改進了矩形腔體射線的接收方法,快速得到腔體腔體口徑面的場強分布。再利用電磁場等效原理,利用口徑表面電磁和磁流求解遠區(qū)散射場。此外本文改進了三維情況下的散射計算公式。
[Abstract]:The study of scattering characteristics of large aircraft is becoming more and more important with the national investment in large aircraft projects. The scattering from the air inlet (cavity shape) is an important part of the aircraft scattering. Although the traditional low-frequency electromagnetic numerical method can accurately solve the scattering of the target object, with the increase of the size, it will take up huge computer resources and the calculation speed is relatively slow. The high-frequency algorithm can be solved quickly, save computer resources and realize fast calculation. In this paper, the scattering principle and calculation of open cavity structure are discussed. The bouncing ray algorithm based on ray tracing Tracing algorithm is a high frequency method for calculating cavity RCS, which is characterized by simple physical concept and easy programming. The algorithm is a combination of geometric optics (GOG) and the equivalent principle of electromagnetic field surface, and can obtain more accurate results. Firstly, the basic methods of ray tracing are analyzed, and the ray emission, path calculation and ray receiving are discussed in detail. Traditional ray tracing can not avoid large-scale line-surface intersection, which takes a lot of time. In order to solve this problem, a space-based ray tracing algorithm is proposed in this paper. Similar to the traditional acceleration algorithm, the propagation space is segmented. The difference is that the new method divides the propagation space into several independent triangular elements (two-dimensional space) or tetrahedral elements (three-dimensional space), using the geometric position relationship between ray and subdivision element. The ray propagation path is calculated quickly and the intersecting test is avoided completely. It is very suitable for ray propagation prediction under complex environment. Secondly, the space split ray tracing algorithm is introduced into the calculation of cavity scattering by bouncing ray method (SBR). The new ray tracing algorithm can quickly track the ray path and field strength. At the same time, the radiation receiving method of rectangular cavity is improved, and the field intensity distribution of cavity aperture surface is obtained quickly. Based on the equivalent principle of electromagnetic field, the scattering field in the far region is solved by using the aperture surface electromagnetic and magnetic current. In addition, this paper improves the calculation formula of scattering in three dimensional case.
【學位授予單位】：南京郵電大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN011

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