Research On The Thermal Radiation Characteristics Of Conformal Dome In The Aero-dynamic Environment

When the aircraft with infrared imaging equipment flight in high-speed within the atmosphere, because of aerodynamic heating effect, the temperature of the dome which is located in front of the aircraft rises rapidly. Due to uneven heating of the dome, the interior of it will cause thermal stress and strain, which results the non-uniform distribution of refractive index field. Meanwhile, high-heat domes will have strong infrared radiation. The radiation interference will seriously affects the image quality. With the increasing of aircraft speed, the disadvantage in terms of aerodynamics of conventional spherical dome makes it not meet the increasing requirements of the aircraft flying at high speed. The conformal dome with a streamlined external surface compensate the aerodynamic disadvantage for spherical domes, but the researches of conformal domes more focus on the aberration correction rather than the study of thermal radiation of aerodynamic effect. In order to overview the superiority of conformal domes, we need to study the thermal radiation characteristics in aerodynamic heating environment.This paper studies the heat radiation effect of conformal domes. Firstly, the conformal dome is divided into a regular grid by using finite element analysis method, and the radiation energy of each grid is calculated; Then using the ray tracing method, the irradiance distribution of three typical surface thermal radiation interference in detector is obtained. Finally, by using the conformal domes model established, three typical domes with non-uniform temperature distributions and refractive index gradients are simulated. The main contents include:(1) The research of flow field characteristics of conformal domes. The finite element model of conformal domes is established basing on the theory of air dynamics and finite element analysis. According to this model, the density field of air flow around the aircraft conformal domes, the temperature field, pressure field and velocity field are calculated.(2) The research of multi-physics coupling characteristics of conformal domes under aerodynamic heating environment. According to the theory of elastic mechanics and heat transfer, combining with the simulation results of flow field of high-speed aircraft, the multi-physics coupling model of conformal domes under aerodynamic heating environment was established by finite element method. Basing on this model, we obtained the temperature field, the stress field, the strain field and the deformation field of conformal domes and their distribution rules, which lay the foundation for computing the thermal radiation.(3) The research of thermal radiation characteristic of conformal domes. Based the simulation results of multi-physics coupling, the radiation and transfer model of conformal domes was established. The software of simulating thermal radiation characteristics of conformal domes was developed. The imaging quality of high-speed aircraft affected by heat radiation for three typical facial forms conformal domes was analyzed.