Optimization design of built-up thermal protection system based on validation of corrugated core homogenization

An optimization procedure aiming to design a built-up thermal protection system is presented in this paper. The built-up thermal protection system comprises of classical Integrated Thermal Protection System (ITPS) and additional layer of insulation material which is attached to the cold surface of ITPS. In this paper, corrugated core sandwich panel which is fabricated using C/SiC composite material is considered as an ITPS when the core void is filled with insulation material. It is found in this paper that for the built-up TPS the temperature calculated based on corrugated core homogenization shows significant deviation from the exact solution. The significant advantage of the built-up TPS in insulation ability compared to the traditional ITPS is validated. An interesting phenomenon is also found that with the increasing insulation ability of the attached insulation, the temperature on the cold surface of the sandwich panel would converge to a stable value. Based on this finding, a two-step design procedure with high accuracy and high efficiency is exploited for the built-up thermal protection system. At the first step, the stable value of temperature on the cold surface of the sandwich panel is obtained utilizing the finite element technique, and is used as the boundary condition needed in the second step. At the second step, the two-dimensional transient heat transfer problem is transformed into a one-dimensional problem based on which the optimal thicknesses of the multiple insulation layers are obtained utilizing the finite difference formulation. Numerical results show that the thickness and the areal density of the built-up TPS can be significantly reduced by considering multilayer design.