High-Fidelity Modeling of the Porous Micro-Structure for Carbon Fiber-Reinforced Ablative Thermal Protection Material

Carbon fiber-reinforced ablative thermal protection materials are widely used in atmospheric re-entry systems to resist aerodynamic heating. To study their microscopic transport characteristics, a high-fidelity modeling method is proposed based on topographic information, which generates an idealized geometric model of the real material's porous micro-structure consisting of fiber arrays. The high-fidelity model is consistent with real material in terms of structural parameters, physical properties, and transport characteristics. Moreover, it is relatively simple and suitable for further flow and ablation simulations. Specifically, X-ray computed micro-tomography is used to acquire real material's topographic information, and then the geometric models of its representative element volumes are reconstructed based on the marching cube algorithm. Representative analysis is performed to obtain the real material's approximate dimensions and confidence intervals of physical properties. Then, a geometric generation algorithm controlled by structural parameters is established to generate an idealized structure using the approximate dimensions. A sensitivity analysis is performed to determine which structural parameters have a great influence on physical properties. These significant parameters are adjusted to generate the high-fidelity model whose physical properties fall within the confidence intervals of real material previously obtained. This ensures consistency between the high-fidelity model and real material regarding structural parameters and physical properties. Ultimately, DSMC simulations are performed under different conditions to compute the permeability of the high-fidelity model. It is found that its permeability obeys the Klinkenberg model, which verifies the validity of the transport characteristics of the high-fidelity model.