Study On Fairing Aerodynamic Thermal Interference Suppression Technology Base On Multi-Spectrum

The fairing of aircraft has the functions of protecting optical system,correcting incoming light and reducing air resistance.However,when the aircraft flying with high speed in high air,the aerodynamic thermal effect is generated due to the friction between the fairing and the atmosphere,which leads its temperature to rise rapidly.It produces radiation interference to the infrared detection and imaging system,increasing the infrared thermal noise of the image,reducing SNR of the image,and degrading the imaging quality and missing the target information.Aiming a problems,this paper focuses on the infrared image thermal noise reduction.A new infrared noise suppression algorithm is proposed based on multispectral information.The new algorithm can reduce the infrared image noise,improve the SNR of image and the imaging quality of the infrared detection system.To a certain degree,it can reduce the target detection time,improve the operating distance and recognition accuracy,and acquire more time follow-up work,such as targeting and avoiding distractions.The main research of this paper includes the following parts:1)Establish and simulate the model of fairing temperature field distribution.Theoretically analyze the aerodynamic thermal effects of the fairing.According to the basic theory of heat conduction and heat transfer in fluid thermodynamics.Segment the fairing by finite element method in MATLAB software,build up the physical model of the temperature field,which generated by friction with air,and simulate the temperature field distribution of the fairing.2)Model and simulate the infrared radiation distribution of fairing temperature field distribution.Base on the infrared radiation theory,simulate the infrared thermal radiation of the fairing in TracePro.Simulate the radiation by Monte carlo method.According to the temperature distribution of the fairing,obtain the infrared thermal radiation of the fairing,and calculate the infrared irradiance of the fairing on the detector after passing through the optical system.3)Use the multispectral information to establish a background noise suppression algorithm.Based on the infrared radiation characteristics of small infrared targets,obtain the multispectral information by using a filter,and build up a multispectral data cubes of targets,background and noises.Using the principle of multispectral infrared radiation temperature measurement,introduce multispectral properties into a new thermal noise suppression algorithm,by using the reverse Monte Carlo method,trace the infrared radiation by the reverse ray,and track the fairing position corresponding to the noise pixel,and build a new algorithm.Building up the mathematical and physical model by MATLAB,simulate the infrared image which after restraining the aerodynamic thermal radiation noise of the fairing.It can be seen from the comparison between the simulation results of the influence of aerodynamic thermal effect of fairing on infrared image and the simulation image resultsafter noise reduction by the new algorithm.The new aerodynamic thermal noise suppression algorithm based on multispectral information in this paper is feasible.It can achieve the purposes of reducing thermal noise,improve infrared image SNR,improve infrared imaging quality and remove thermal infrared radiation interference.