Equivalent Modeling and Calculation of the Infrared Characteristics of Combined Multi-Regular Triangular Pyramid Cavity Structures Based on Cavity Radiation Theory.

To address the high computational complexity of evaluating the infrared radiation characteristics of combined multi-regular triangular pyramid cavity structures and the low efficiency of direct numerical simulation, this paper proposes an equivalent modeling and computational method for infrared characteristics based on cavity radiation theory. Taking a regular icosahedral corner reflector as the object of study, the complex multi-cavity structure is first decomposed into several regular triangular pyramid cavity units. Based on cavity radiation theory, first- and second-order approximate models for the effective emissivity of the opening of a single regular triangular pyramid cavity are derived, and the average effective emissivity is then determined in conjunction with geometric relationships. Subsequently, using the calculated effective emissivity of a single cavity, the multi-cavity composite structure is radiatively equivalent to a regular solid with the same outer contour and uniform surface emissivity, thereby enabling rapid calculation of the infrared radiation characteristics of the complex target. An observation network comprising 82 viewpoints was constructed, and simulation-based validation was conducted under varying temperature, size, and material-emissivity conditions. Based on the data analysis, an empirical correction term was subsequently introduced to compensate for the errors. The results show that, within the emissivity range of 0.2-0.9, the average error between the corrected equivalent model and the simulation results of the original complex structure can be controlled within 1%. Moreover, the model exhibits good stability with respect to variations in target temperature and geometric size. While maintaining computational accuracy, the proposed method improves computational efficiency by approximately 3.8 times compared with direct simulation. The study demonstrates that the proposed method can effectively preserve the main infrared radiation characteristics of combined multi-regular triangular pyramid cavity structures and can provide methodological support for the rapid evaluation and engineering design of the infrared characteristics of such complex cavity targets.