Thermo-Chemical Phenomena Simulation for Ablation.

摘要

Three major objectives of the basic research grant have been met. First, a physic based chemical kinetic model for high-temperature gas is developed and verified by comparing with data from the RAM-C-II probe and the Stardust sample return capsule. In the absence of an externally applied electromagnetic field, the Lorentz force and Joule heating in the globally neutral ionized gas is insignificant. Meanwhile the energy transfer from the translation and vibration degrees of freedom to electronic excitation is found to be negligible and the energy exchange is dominated by the chemical process for conductive-convective heat transfer. A simplified and more efficient energy conservation formulation has been verified against the published results of the fastest reentry objective Stardust capsule. Second, a multi-spectral group approach for simulating nonequilibrium radiation heat transfer is accomplished. Accurate simulation for axisymmetric and three-dimensional configuration using the half-moment method and tracing technique for solving the nonequilibrium radiation intensity equations. The numerical result not only generates equally accurate prediction from the NASA ST centers, but also reveals for the first time the radiation frequency shift phenomenon. Third, in analyzing radiative heat transfer for thermal protection, a rigorous interface boundary condition for the ablating material has been derived via the Reynolds transportation theorem. The basic formation explicitly includes the surface ablation and recession rate as well as the stress component for evaluation.