Abstract For a high-speed infrared guided missile, the supersonic mixing layer over the optic window causes the aero-optical transmission effects such as target image blurring, jittering, and offsetting. The large eddy simulation is used to simulate flow of the supersonic mixing layer and the ray tracing is used to compute transmission path of the beam passing through a vortex, and three parameters are proposed to evaluate the aero-optical transmission effects of each case. The results show that the larger vortex will cause the more severe optical phase distortion, the weaker far-field peak intensity, and the larger deviation of transmission path. The ray passing through the vortex core usually has the largest deviation if there is no density difference between the upper and lower inlet fluids. A significant finding is that density difference of the two inlet fluids will exacerbate the aero-optical transmission effects Under the premise of pressure matching, a suggestion to reduce aero-optical transmission effects suffered in the practical engineering is that outlet density of the jet should be as close as possible to that of the freestream. In the end, the quantitative relationship between fluid density fluctuation and beam transmission path is derived.

中文翻译：

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超音速混合层涡流对航空光传输效应的评价

摘要 对于高速红外制导导弹，光学窗口上方的超音速混合层会引起目标图像模糊、抖动、偏移等气光传输效应。大涡模拟用于模拟超音速混合层的流动，射线追踪用于计算光束通过涡流的传输路径，并提出三个参数来评估每种情况下的气动光学传输效果。结果表明，涡流越大，光相位畸变越严重，远场峰值强度越弱，传输路径偏差越大。如果上下入口流体之间没有密度差异，穿过涡核的射线通常具有最大的偏差。一个重要的发现是两种入口流体的密度差异会加剧气光传输效应 在压力匹配的前提下，在实际工程中减少受到的气光传输效应的建议是射流的出口密度应为尽可能接近自由流。最后推导出流体密度波动与光束传输路径的定量关系。