Study on aero-optical effect of a hypersonic missile infrared image guide

Abstract

ABSTRACT When a hypersonic missile with a side mounted IR seeker is launched in the atmosphere ea serious aero-optical effect is formed and affects the quality of the detector’s imaging.And in the course of the missile flight time,aero-optical effects changes over time, which makes real-time, accurate correction of opti cal distortion becomes very difficult. Therefore, it is necessary to study the relationship between the optical distortion and time.In this paper, Fluent,a computational fluid dynamics(CFD) internet applications is used to make researches on effect of optical transmission of the flow field outside the IR window. And a thermal finite element analysis (FEA) of an IR window is used to study the aerodynamic heat effect. Keywords: aero-optic effect, wavefront error, birefringen ce, thermo-optic effect,elastic-optic effect, 1. INTRODUCTION When a missile with a side mounted IR seeker is launched in the air at a high speed, a complex aerodynamic flow is formed over the optical window. Image aberration distortion and boresight shift vary according to flow conditions and the thermal state of the optical window system. And the seeker ’s capabilities of target detection, tracking and recognition are reduced. So it has certain theoretical and practical significance to study the aerodynamic flow and its aero-optic effect for a side mounted IR window. Aero-optic effect includes high-speed flow-field optical transmission distortions and optical dome aerodynamic heat effect. Because these two effects have different time-frequency characteristics, the wavefront aberration is time-varying.In this paper, fluent,a software of Computational fluid dynamics (CFD) is used to analyse the high-speed flow-field optical effects. Also,ansys,a software of finite element analysis (FEA) is used to calculate the optical dome aerodynamic heat effect.