Theoretical prediction of thermal conductivity for thermal protection systems

The present work is aimed to evaluate the effective thermal conductivity of an ablative composite material in the state of virgin material and in three paths of degradation. The composite material is undergoing ablation with formation of void pores or char and void pores. The one dimensional effective thermal conductivity is evaluated theoretically by the solution of heat conduction under two assumptions, i.e. parallel isotherms and parallel heat fluxes. The paper presents the theoretical model applied to an elementary cubic cell of the composite material which is made of two crossed fibres and a matrix. A numerical simulation is carried out to compare the numerical results with the theoretical ones for different values of the filler volume fraction.

► Theoretical models of the thermal conductivity of an ablative composite.
► Composite material is made of two crossed fibres and a matrix.
► Three mechanisms of degradation are investigated.
► One dimensional thermal conductivity is evaluated by the heat conduction equation.
► Numerical simulations to be compared with the theoretical models.