Analysis of factors influencing the infrared temperature measurement of targets inside a cavity based on radiation transfer simulation

Infrared radiation thermography provides two-dimensional temperature field distributions and is widely used in experimental diagnostics in aerospace, materials processing, and related fields. However, when measuring targets inside a heated cavity, the complexity of radiation transport often leads to substantial deviations between the recorded temperature and its real value. This work employs a numerical solution of the radiative transfer equation based on the discrete ordinates method coupled with the differential element method (DOM–EDM) is employed to model radiation transport during infrared temperature measurement within a cavity and to analyze the associated influencing factors. A geometric model of a representative cavity test section with multiple infrared windows is constructed, incorporating wall and target surface radiative properties, spectral absorption and scattering of the participating medium, and spatially varying refractive index effects. The combined influence of these multiphysics factors on infrared temperature measurement accuracy is systematically investigated. The results indicate that increasing the target emissivity enhances its radiative signal, whereas reducing the cavity-wall emissivity suppresses reflected-radiation interference. Medium absorption induces a positive measurement bias, which becomes more pronounced with increasing absorption coefficient. Scattering redistributes radiative energy and strengthens temperature-field nonuniformity. Spatial refractive-index gradients cause ray deflection and produce distortions in the reconstructed temperature field. Despite multiple sources of interference, the central region of each observation window consistently provides the highest measurement reliability and is therefore recommended as the preferred sensing location. This work establishes a comprehensive analysis framework for infrared temperature-measurement errors in enclosed cavities, elucidates the intrinsic links between radiation-transport mechanisms and measurement deviations, and provides theoretical foundations and numerical references for error correction and measurement-strategy optimization under complex radiative environments.