Computation and analysis of IR imaging impacted by the high-speed flow-field

Aero-optic effect induced by the flow-field outside the IR seeker optical window is one of the problems needed to be solved in designing a high-speed interceptor. When IR signatures form the target throughout the high-speed flow-field, the IR image on the seeker will be shifting, blurring and even jittering. These effects bring errors of position setting, and degrade the intercepting precision. Based on the thermochemical non-equilibrium Navier-Stoke equations, the highspeed flow-field is simulated numerically. The Ray-tracing and physical-optic methods are used to get the OPD and PSF, which can describe the shifting and blurring of IR image. The affect factors of IR image shift and attenuation are considered, including Mach number, attack angle, altitude, incidence angle and IR wavelength. As a result, the aero-optical effects under 30km altitude have obvious influence on IR imaging,and increasing the incidence wavelength can reduce the attenuation of IR image intensity.