Mathematical model of the effective radiation of airborne objects accounting for upward and downward radiation in a cloudless atmosphere in the infrared wavelength range

Subject of study. The effective radiation of airborne objects in the wavelength ranges of 3–5 µm and 8–14 µm is studied. Aim of study. The aim was to develop a mathematical model of the effective radiation of airborne objects in the wavelength ranges of 3–5 µm and 8–14 µm. The model was constructed by solving a three-dimensional problem of complex heat transfer on a surface using the finite volume method in the ANSYS software environment. The proposed model accounts for the upward and downward fluxes of solar and thermal radiation in a cloudless atmosphere. Method. The energy characteristics of the effective radiation (intrinsic and reflected) of airborne objects were determined by solving the three-dimensional problem of complex surface heat exchange using the finite volume method in the ANSYS software environment. In addition, the radiation transfer equation for a cloudless atmosphere in the wavelength ranges of 3–5 µm and 8–14 µm was solved. The atmosphere was represented by a system of layers, and each layer was characterized by a constant temperature and stable concentrations of water vapor and carbon dioxide. Main results. A mathematical model of the effective radiation of airborne objects was developed. The model enables the calculation of the radiation characteristics of objects while accounting for their parameters, including the power of internal sources, optical and thermophysical surface properties, and object geometry. It also considers the variability in atmospheric, terrestrial, and solar radiation at different altitudes, times of day, and seasons. The maximum deviation of the simulated effective radiation brightness from that obtained experimentally is 15%. Practical significance. The results of this study can be used to simulate the thermal signatures of airborne objects and to evaluate the performance of monitoring systems for airspace and those for the Earth’s surface in the infrared wavelength range.