摘要
以平流层飞行器用星光导航为背景,研究在平流层内星光传输过程受大气湍流的影响机理,揭示平流层中星光的衰减规律,为建立平流层星光导航星库以及电耦合器件(CCD)所摄取的星图补偿方法提供理论依据。研究提出将流场密度和流场密度脉动变化大的区域划分为宽度为L的特性截面,并基于几何光学法及统计光学理论分别计算星光穿过各特性截面后产生的光线偏折及平均光强衰减,进而推导整个平流层内星光传输过程中的能量衰减变化曲线。采用基于k-ε双方程湍流模型的雷诺平均法计算不同极端情况下的大气湍流场密度及密度脉动分布。通过计算机数值仿真表明:星光穿过具有湍流的平流层时将发生明显偏折,其偏折程度与流场密度值有关;同时星光光强衰减,衰减程度与流场密度脉动值有关。
Based on the satellite celestial navigation,this paper studies the mechanism of the starlight transmission in atmospheric turbulence in the stratosphere,reveals the attenuation law of the starlight during transmission,and provides the theoretical basis for establishing the navigation star database and the compensation algorithm of a charge coupled device(CCD) star map.Segments with a certain thickness is proposed by intercepting the sections at the boundary of which the density and density fluctuation of the turbulent field has changed seriously.At the mean time the deflection and average intensity of the starlight after transferring through each section is calculated respectively according to the geometrical optic method and the statistical optic theory,and then the energy attenuation curve of the starlight during transmission through the whole stratosphere is derived either.The k-ε turbulence model is adopted to simulate the density and density fluctuation field of the atmospheric turbulence in different extreme natural cases.The results of the simulation show that the starlight will be deflected obviously and the starlight intensity will decay after traveling through the stratosphere with turbulence,where its deflection and attenuation are related to the density and the density fluctuation of the turbulence,respectively.
引文
[1]杨博.航天器星敏感器自主定位方法及精度分析[J].宇航学报,2002,23(3):81-84.[Yang Bo.The method of autonomous position determination using star sensor and analysis of precision for spacecraft[J].Journal of Astronautics,2002,23(3):81-84.]
[2]徐光勇.大气湍流中的激光传输数值模拟及其影响分析[D].成都:电子科技大学,2008.[Xu Guang-yong.The numerical simulation and impact analysis of laser propagation in the atmospheric turbulence[D].Chengdu:University of Electronic Science and Technology of China,2008.]
[3]刘景源.SST二方程湍流模型在高超声速绕流中的可压缩修正[J].宇航学报,2012,33(12):1719-1726.[Liu Jingyuan.Compressibility correction for the SST two equation turbulence model in hypersonic flows[J].Journal of Astronautics,2012,33(12):1719-1726.]
[4]杨云军,马汉东,周传江.高超声速流动转捩的数值研究[J].宇航学报,2006,27(1):85-88.[Yang Yun-jun,Ma Han-dong,Zhou Chuan-jiang,Numerical research on supersonic flow transition[J].Journal of Astronautics,2006,27(1):85-88.]
[5]徐向博.大气湍流对激光传输的影响研究[D].长春:长春理工大学,2011.[Xu Xiang-bo.Effect on laser propagation in the atmospheric turbulence[D].Changchun:Changchun University of Science and Technology,2011.]
[6]续敏,王建立,王建军,等.CCD在卫星星等测量中的应用[J].半导体光电,2008,29(1):447-450.[Xu Min,Wang Jian-li,Wang Jian-jun,et al.Application of CCD in satellite magnitude measurement[J].Semiconductor Optoelectronics,2008,29(1):447-450.]
[7]洪汉玉,张天序,余国亮.基于Poisson模型的湍流退化图像多帧迭代复原算法[J].宇航学报,2004,25(6):649-654.[Hong Han-yu,Zhang Tian-xu,Yu Guo-liang.Iterative multiframe restoration algorithm of turbulence-degraded images based on Poisson model[J].Journal of Astronautics,2004,25(6):649-654.]
[8]Ruan W C,Cen Z F,Li X T,et al.Simulation and analysis of nonlinear self-focusing phenomenon based on ray-tracing[J].Acta Physica Sinica,2013,62(4):044202.
[9]Xue B D,Zheng S L,Cui L Y.Transport of intensity phase imaging from multiple intensities measured in unequally-spaced planes[J].Optics Express,2011,19(21):20244-20250.
[10]Paolucci S.Direct numerical simulation of two-dimensional turbulent natural convection in an enclosed cavity[J].J.Fluid Mech.,1990,215:229-262.
[11]Jones W P,Launder B E.The prediction of Laminarization with a two-equation model of turbulence[J].Journal of Heat and Mass Transfer,1972,15(2):301-314.
[12]王润轩.一种变折射率光学系统光线追迹的新方法[J].激光技术,2004,28(6):664-666.[Wang Run-xuan.A new method of ray tracing in gradient index optics[J].Laser Technology,2004,28(6):664-666.]
[13]刘维慧.激光在大气湍流中传播时光强起伏的初步分析[D].成都:电子科技大学,2004.[Liu Wei-hui,Preliminary analysis of the the laser intensity fluctuation during transmission in atmospheric turbulence[D].Chengdu:University of Electronic Science and Technology of China,2004.]
[14]李桂春.大气光学[M].北京:国防工业出版社,2006.