Modeling of Material-environment Interactions for Hypersonic Thermal Protection Systems PDF Download

Author: Samuel Y. Chen
Publisher:
ISBN:
Category : Aerospace engineering
Languages : en
Pages : 220

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Book Description
Hypersonic vehicles operate in extreme conditions, experiencing high heating loads, gas temperatures often exceeding 10,000 K in the shock layer, and oxidizing environments. Thermal protection systems (TPS) are thus a vital component to the design of a hypersonic flight vehicle. The overarching goal of this work is to characterize and model the material-environment interactions between TPS materials and the hypersonic flowfield -- these dictate the thermal and chemical behavior of the TPS. Two materials are investigated: ablative materials, which degrade during exposure to flight conditions, and ultra-high temperature ceramics (UHTCs), which exhibit refractory and oxidation-resistant properties. A coupled framework involving computational fluid dynamics (CFD), material response, surface chemistry, and radiation is used to simulate experiments and evaluate the material models. This work is divided into three main parts. The first part of this dissertation demonstrates how radiative emission can be used in simulations to investigate the chemical kinetics of ablative materials. CFD--radiation simulations are performed in collaboration with high-temperature plasma experiments, using radiative emission measurements in the reacting boundary layer to validate the chemical models. The second part focuses on the development of a thermodynamic model describing oxidation of silicon carbide (SiC), a UHTC material. The model is validated against experimental data in the literature, and coupled CFD simulations of SiC oxidation are performed using the model. Predicted surface temperatures and simulated emission spectra are shown to be in good agreement with experimental data. The third part details the development and evaluation of a thermodynamic model for zirconium diboride (ZrB2) and ZrB2-SiC oxidation, a UHTC composite. Overall, thermodynamic modeling approaches are sufficient to describe the equilibrium oxidation behavior of these TPS materials. However, limitations of the proposed models are also discussed, motivating the need for higher-fidelity finite-rate models and additional experimental data.