A solar radiant heating apparatus for measuring the thermal behavior of silica fiber phenolic composite for thermal protection applications

A solar radiant heat flux experimental apparatus was designed and built with a complete set of instrumentation. The sunlight, which firstly converged by Fresnel lens and then secondly converged by prism, was used as the energy source. The test bench was capable of producing a known high radiant heat flux in a short time and was used to investigate the thermal and ablation behaviors of thermal protection materials designed for space vehicle. The thermocouples were embedded in the test specimen to monitor the time-dependent temperatures. Also, the thickness of the heat affected zone was determined by sectioning the specimen after thermal exposure in millimeter segments. These experimental data are suitable for use in verification of numerical models. A mathematical model for the coupled temperature-diffusion-expansion problem of porous materials was proposed. The thermal responses of a silica fiber phenolic composite were predicted and compared with experimental values for the same boundary and initial conditions to assess the accuracy of the model.