| Airborne warning and control system(AWACS) is a kind of aircraft with command and warning functions, which is the command center in modern air combat. With the importance of AWACS in modern air combat becoming more and more obvious, effective detection and attack to AWACS is important for the victory of war. In recent years, the wide application of stealth materials brings the development of radar technology into trouble. In contrast, this kind of target has high speed and intense infrared radiation, which means that we can use infrared detection technology to detect and recognize them. Infrared detection and imaging for AWACS work through its obvious infrared radiation, which can help to realize detection and attack to AWACS and have important research significance.This paper analyzes and summarizes the characteristics of near space atmospheric environment and proposes a calculation model of atmospheric transmittance. On this basis, it analyses atmospheric mean transmittance under short, medium and long wavelength. This paper also focuses on AWACS modeling and CFD simulation based on the real flight environment. According to the simulation data, it calculates the infrared radiation characteristics of the skin of AWACS by use of the relevant algorithms. Based on the result, the paper also gets the infrared image of the skin by using the method of spatial coordinate transformation and projection mapping. Finally, this paper simulates and analyzes fairing aerodynamic heating, which is taken as a kind of environmental noise. At the same time, it studies the influence of this thermal noise on imaging and detection and then put forward indexes of temperature control on fairing. In this paper, the research is divided into four parts:1. Based on the basic principle of infrared radiation, this paper introduces the molecular density of the atmosphere、temperature and pressure from near-space and raises the calculation steps of atmospheric average transmittance. Besides, according to the flight characteristics of AWACS, average atmospheric transmittance under different detection travel is computed, which provides important parameters for infrared radiation characteristics analysis and simulation of infrared image.2. In view of the infrared radiation characteristics of AWACS, this paper studies the infrared characteristics of AWACS skin. After finishing AWACS entity model by SolidWorks software, the simulation model is completed and meshed by ICEM-CFD software and then Fluent software is used for CFD simulation of the model. Taking solar radiation into consideration, the temperature distribution of the skin is got. Finally, combining occlusion and hidden correlation algorithm, this paper computes the infrared radiation characteristics of the skin from different directions and angles, and then compares the result with related data.3. According to the data of infrared characteristic simulation and analysis, this part builds the infrared imaging simulation system model. According to the model, this part uses the method of coordinate transformation and projection mapping to get the infrared simulation image, which also considers the influence of target background and noise.4. Finally, this part simulates fairing model and analyses its aerodynamic heating, which is taken as ambient thermal noise. Based on the result, this part studies the influence of this thermal noise on imaging and detection and then put forward indexes of temperature control on fairing according to system SNR. |
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