Imaging deviation through non-uniform flow fields around high-speed flying vehicles

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• 作者：Liang Xu^a ; ^b ; Yuanli Cai^a ; ^{ylicai@mail.xjtu.edu.cn} ; ^{alvinlxu@gmail.com}
• 关键词：Imaging ; Imaging deviation ; Aero-optics ; Non-uniform flow field
• 刊名：Optik - International Journal for Light and Electron Optics
• 出版年：2012
• 期刊代码：13_00304026
• 类别：et
• 出版时间：July, 2012
• 卷：123
• 期：13
• 页码：1177-1182
• 文件大小：552 K

摘要

The non-uniform flow field around high-speed flying vehicle 鈥渂ends鈥?the ray and imposes a deviation at the end of the propagation path. This imaging deviation is a kind of aero-optic effect. In this paper, we catalog the factors that influence the deviation into two classes: the vehicle-related factors and the flowfield-related factors. Flow density computation and density-refractive index conversion are discussed. A backward ray-tracing scheme is proposed. The deviations, the propagation path distances in the non-uniform flow field, and the density distributions along propagation paths for two different flying cases are computed. Three flowfield-related factors should be considered in order to reduce the deviation: the propagation path distance in the non-uniform flow field, which should be as short as possible; the angle of incidence at the freestream boundary, which should be as small as possible; and the density distribution along propagation path in the non-uniform flow field, which should be as flat as possible.