Effect of external heat flux on the thermal diffusivity and ablation performance of carbon fiber reinforced novolac resin composite

Abstract

Ablation is an effective and reliable method largely used in aerospace structures and other high temperature conditions to protect the payload from the damaging effects of external high heat flux. In an ablation process, the high heat fluxes are dissipated by the material through a series of endothermic processes. This finally leads to the loss and the consumption of the material itself. The ablative material keeps the surface temperature within a certain range, and as a consequence an increase of the heat flux will not cause a consistent temperature rise, but will bring about an increase of the surface recession rate. The objective of this work is to give information on the effect of the external heat flux to evaluate effective thermal diffusivity behavior and ablation performance of carbon fiber reinforced composite based on novolac resin. Here, we calculate the effective thermal diffusivity of this composite at different heat flux conditions using inverse solution technique of conservation equations of mass and energy. The ablation performance evaluation is based on experimental transient ablation rate measurement in oxyacetylene flame test. The results of this work explained the ablation process and thermal diffusivity behavior of this composite as a high performance heat shield at high external heat fluxes.