Effect of meso‐structure characteristics on surface emissivity of 2.5D Woven ablative composite for thermal protection

Abstract Surface emissivity is an essential parameter for thermal radiation, which greatly influences thermal protection materials (TPMs) under high temperature. In the present study, dual‐scale models of 2.5D woven carbon fiber fabric reinforced resin‐based composites are built with different weaving parameters of fabric, to investigate the meso‐structure influence on the surface emissivity, and the surface emissivity for different composites is calculated based on discrete ordinate method (DOM). Two morphological indexes are proposed to further analyze the effect of meso‐structure characteristics on emissivity. The results show that the surface emissivity is mainly determined by the ablated woven composite within a certain depth. More compact in‐plain weaving architecture improves surface emissivity, while more compact through‐the‐thickness weaving architecture reduces the surface emissivity of 2.5D woven ablative composites. The meso‐structure with a lower roughness factor and a higher specific surface area leads to intense surface radiation. This study can provide scientific guidance for the design of 2.5D woven ablative composite for thermal protection.