Real-time estimation of thermal boundary conditions and internal temperature fields for thermal protection system of aerospace vehicle via temperature sequence

Abstract

Aerospace vehicles go through extremely aerothermal heating upon entry into the atmospheric, which need to employ the reliable thermal protection system (TPS). The boundary heat flux and inner temperature information for aerospace vehicles are required to design the TPS. The direct measurement for temperature and heat fluxes is quite difficult mission. In this study, unscented Kalman filtering, is an indirect measurement method based on inner surface temperature information and is introduced to reconstruct the transient heat flux and inner temperature fields of TPS in real-time, which is regarded as a graded index medium. The finite volume method and discrete ordinate method are utilized to solve the energy equation and radiative transfer equation to obtain measurement temperature, respectively. Based on the measurement temperature signal, the unscented Kalman filtering technique is applied to reconstruct the surface heat flux and inner temperature field of the TPS. Simulation results indicate the time-dependent boundary heat flux and inner temperature fields can be estimated using proposed method. The effects of thickness, refractive index, measurement noise, and process noise on the reconstructed results are studied in detail. Retrieval results show the proposed technique is more precise and robust than Kalman filtering method in the nonlinear system.