不同对流马赫数下细光束畸变特性研究

为了探讨混合层可压缩效应对细光束成像变形特性的影响，利用理论分析和相机成像技术研究了不同对流马赫数下细光束成像的畸变特性．通过理论分析首先揭示了图像模糊程度的判据之一“穿越混合层后细光束零级衍射斑直径”与流场特征参数（如对流马赫数、自由流速度、密度比等）之间的关系；实验结果还发现随着对流马赫数的提高，零级衍射斑直径增长速度加快，图像的模糊程度提高．此外理论分析结果为将来实验方案设计提供了指导．

Investigation on thin distortion of small light beam at different convective Mach number

In order to investigate shape distortion of small light beam at different convective Mach number （Mc）, the technique of CCD camera imaging has been used. The theoretical analysis presents the relation between growth rate of diameter of small beam light （passing through the compressible mixing layer） and flow characteristic parameters （such as convective Mach number, free stream velocity, free stream density ratio and so on）. The experimental results show that Airy spark diameter increases fast with the increase of convective Mach number, which implies more indistinct image. In addition, the theoretical results also point out the direction of further experimental design.