Study On Infrared Reflection Characteristics Of A Type Aircraft Surface

The surface of the aircraft will be exposed to environmental radiation such solor radiation,ground and atmosphere radiation,solar radiation reflected from the ground when the aircraft is flying in the air.When the infrared guided missile detector captures the target,on the one hand,the surface reflection ambient radiation is the radiation source detected by the detector,so the detector can track the reflection of the environmental radiation and strike the target.On the other hand,due to the variability of environmental radiation,surface reflection from ambient radiation may become a disturbance item when the infrared guided missile tracks the target,which can lead to the aircraft off target.Therefore,the research of infrared reflection characteristics of aircraft is of great significance for the implementation of operational plans,identification of the target infrared,experiment of infrared guided missiles.The infrared reflection characteristic of a type aircraft surface is studied in this thesis.In order to obtain the surface reflection characteristics of the aircraft material,the bidirectional reflection distribution function(BRDF)models include Schlick model and Cook-Torrance model are established firstly.According to the research of the BRDF model,it is found that the reflection coefficient and roughness factor in BRDF model are the main factors affecting BRDF function.Then the BRDF parameter inversion method is established based on the stochastic inertia weight particle swarm algorithm and different bidirectional reflection function physical models.The BRDF parameters of aluminum alloy and titanium alloy are reconstructed by the inversion method according the known literature data.Results demonstrate that the stochastic inertia weight particle swarm inversion model is correct.Further,the infrared reflection characteristics of the aircraft surface are studied based on the BRDF model.The three-dimensional model of the aircraft and the division of the aircraft grid are completed by Catia and GiD respectively.Then the the coordinate transformation relationship is established based on the derived grid data.And the radiation occlusion factor of the aircraft surface is calculated by the inverse monte carlo method.To obtain the atmospheric transmittance,the automated calculation program that call MODTRAN is writed in Fortran.By the calculating of ambient radiation received by the aircraft surface,it is found that the ambient radiation on the aircraft surface is related to the flight attitude of the aircraft,the local time,position,and the detection band.Finally,The radiation reflected by the aircraft is calculated,the result show that the BRDF model is more reasonable than the diffuse reflection model to calculate the surface reflection characteristics of the aircraf,and the reflected radiation distribution of the aircraft surface under different reflection angle.Therefore,in order to accurately capture the target,it is necessary to select a reasonable operational plan based on the local date,time and position,the detection band,and the relative aircraft position.