Numerical simulation and analysis of aero-optical effect of the 3D side window

When the flight with an optical window is flying in a high speed, the temperature and the refractive index of the air around it will be changed because of the friction, and this will make the image on the detector blurring and shifting, which will degrade the detecting precision greatly. This paper chooses a typical kind of model for the research. Ansys is used in order to gain the temperature field around the hood in real size instead of an assumptive and approximate model. So the refractive index of the air could be worked out. On this basis, the offset and the blur of the image could be figured out using the ray tracing method. Considering of the characters of the grid points distribution and the huge amount of data exported from Ansys, self-adaptive step length tracing method and interpolation method are used in order to shorten the run time and guarantee computational precision at the same time instead of the adaptive variable step method and complicated gradient algorithm. In this study, 3D simulation and programming results under different flight conditions are discussed. The results clearly show the relationship between the image quality and the flight altitude, wavelength and focal length.