Thermal Response of an Orthotropic Non-charring Ablative Material

In this paper, the thermal response of orthotropic carbon–carbon is studied. In the first step, non-charring materials ablation is implemented into a finite volume solver. Carbon–carbon ablative thermal behavior is studied under a time-dependent heat flux. The equilibrium surface thermochemistry model of carbon ablation in air including the diffusion and sublimation along with energy source term, heated wall recession and material properties are all applied in FLUENT 6.3 solver via user-defined functions. Stagnation point temperature, recession and net heat flux for the isotropic case are compared with the published one-dimensional finite difference results. Subsequently, the effects of orthotropic conductivity of the material on surface temperature, ablation mass flux, recession rate of the heated wall and the temperature distribution through the material are described. Results indicate that higher surface temperature and ablation mass flux as well as lower interior temperatures are achieved by the orthotropic material response, compared to the isotropic one. The same conclusion can be made by increasing the ratio of “in-plane” to “through-the-thickness” conductivities. In brief, this work presents a methodology for modeling two- and three-dimensional non-charring material ablation within FLUENT solver to study the thermal response of an anisotropic ablator, sharp geometries and metal–insulator interface where a classic one-dimensional approach is inaccurate.