The Simulation Analyses Of Aero-optics Effects Of Supersonic Optical Hood

When a high-speed aircraft is in flying process, as the aircraft is moving so fast, the optical hood or the optical window will generate severe friction by surrounding air. The temperature of the aircraft’s outside surface will also raise as the friction occurs. With the emergence of shock wave, turbulent layer, boundary layer, there will be an irregularity gradient refraction index field, and that is the aero-optical effect. Aero-optical effect will result in the skewing, shake and blur. The optical imaging system of seeker will receive an image with aberration. Perhaps the image will also have optical path differences and it will generate wave aberration. In severe cases, the temperature difference between inside and outside will lead to the deformation of the optical window and the image will have distortion. The imaging quality will be effected seriously. So we can conclude that aero-optical effect will impair the imaging quality and reduce the general ability of robus t classification and tracking of objects. Thus it can be seen that the research of aero-optical effect has an important significance.First, change the regime of flight in Fluent, research the aero-optical effect of boundary layer and shock wave. Adjust the angle of attack, temperature, flight height, flight speed and the angle of incidence. According to the research of the data, figure the influence to the flow field around the aircraft. The result will be used in establishing correct structural model, creating appropriate computational grid and setting up various solution parameters.Then, by the research of hydromechanics and computational fluid mechanics, learning the method of application of Fluent which is a simulation software and Gambit which is a modeling software is very important. Then determine the parameters of model, establish structural model and divide the redistrict grid. The boundary conditions, solver and solving equation also need to be determined. After analysis, the research in this pape r adopts a grid which is inhomogeneous to divide the flow field around the aircraft.The research in this paper analyzed the mode of transmission in flow field. By combine the ray tracing method and physical optics, create a fixed-step ray tracing method which can simplify the difficulty of modeling in meanwhile the computational accuracy will not be impaired.Fluent can generate the discrete distribution of air density of the peripheral region of optical window. Using MATLAB to read the data and establish the discrete distribution of refractive index. The supposed object is a point light source in infinity. Using the ray tracing method which is mentioned before is to get the wave aberration of the surface of optical window. The complex amplitude will be figured out by Fourier transform the wave aberration, to get the point spread functionIn the end, it analyzes the result of the research. Compared the simulation result with theoretical value and analyzed the theoretical explanation of the result.