Theoretical And Experimental Research On Infrared Stealth With Pavement Background

With the development of infrared detection technology, the space and spectral resolutions of the infrared detection equipment are get higher, which induces the urgent requirement of the infrared defense. It can be expected that the effective mean of the infrared stealth will be to keep the infrared radiation characteristics of the object to be protected and the background identical, in other words, to make the object to be protected and the background have the same surface temperature while their infrared emissivities are identical. Therefore, this work focused on how to make the surface temperature of the object to be protected the same as that of the typical pavement background via the regulation of the former’s thermophysical properties and thickness with the same radiative properties subjected to the same ambient conditions.At the beginning, based on the measurement principle of a thermal imager, the technical requirements of the infrared stealth was elucidated. It was obtained that the effective mean to achieve the same infrared radiation characteristics of the object to be protected and the background was to keep their surface temperatures and infrared emissivities identical.Therefor, one-dimensional heat transfer models for the object to be protected and the typical pavement background was established to explore the influences of the former’s thermophysical properties on the surface temperature difference (STD) between them subjected to the same periodical ambient conditions when their infrared emissivities are the same. It was elucidated that the STD was dominated by the thermal inertia of the imitative material, which composes the objected to be protected. When its dimensionless thickness is not less than 1.0, the STD is invariable if its thermal inertia is a constant. When the imitative material’s dimensionless thickness is less than 1.0, the STD is influenced by both the thermal inertia and the dimensionless thickness of the imitative material. Furthermore, if the imitative material’s dimensionless thickness is much less than 1.0, the STD is determined by the product of the thermal inertia and the dimensionless thickness of the imitative material. Especially, if the thermal inertia of the imitative material is the same as that of the road’s surface layer, the STD approaches zero, as long as the dimensionless thicknesses of the imitative material and the surface layer are both not less than 1.0. Meanwhile, the practical applications of several materials were also considered and the advantages and the disadvantages of them were proposed. The imitative material can be both light and thin via the application of the phase change material (PCM) for a preset STD because of its high specific heat capacity during the phase transition process.Furthermore, the application of the PCM for some typical objects was given. Based on the effects of the PCM on the surface temperature regulation of the plate, the thermal protection schemes were proposed for three typical objects subjected to the typical daily ambient under concrete road, asphalt road and grassland backgrounds in different areas. The results were verified via the experiment.